Clubjazz - Honda Jazz & HR-V Forums

Honda Jazz, HR-V & Hybrid Forums => Honda Jazz Mk3 2015 - 2020 => Topic started by: Sidot on February 12, 2016, 02:52:13 PM

Title: MPG for those interested.
Post by: Sidot on February 12, 2016, 02:52:13 PM
Collected car mk3 SE 29.9.15.
10 miles on the clock .....now 2131.
46.66 gallons used 1818 miles covered = overall 38.96 mpg.
All "around the town Autumn and Winter" driving, except one 197 mile trip to South Wales.
I drive carefully and try for best optimum.
Only slightly better than mk2 1.2 ltr. Which was about 34/35 comparing like for like.
I see a Mk2 go past and still admire the smooth lines whilst trying to get my Honda Connect to do what I want it to !!!

Edit by Admin: made topic a sticky topic.
Title: Re: MPG for those interested.
Post by: 7800manor on February 12, 2016, 03:51:02 PM
I pick up my Jazz SE on the 23.12.15 and to date I have done 850 miles filled up today for the fourth time and the
        clocks tell me the average M P G is 48 which I think is not to bad , K L J
Title: Re: MPG for those interested.
Post by: John Ratsey on February 12, 2016, 07:06:23 PM
My Mk 3 is just over 2000 miles and averaging 56 mpg. However, a lot of the miles were accrued in September and October as longer trips in better weather. If I don't need to go anywhere during the winter months then I don't go. The computer strugges to report much over 40 mpg for shorter trips in winter and I know that it is optimistic.

Wait for some nice summer weather and the mpg will take an upwards leap plus, I hope, there will be a gradual improvement as the engine gets run on. The target for my Mk 3 is to equal the 58.8 mpg which my previous hybrid Jazz had averaged. However, if Honda are promising a 99g/km CO2 Civic with 1 litre 3 cylinder turbo engine then the same engine in the Mk 3 Jazz (if/when it appears as an option) could give significantly better mpg than our current engines.
Title: Re: MPG for those interested.
Post by: John Ratsey on March 05, 2016, 02:20:24 PM
Made a trip from Swindon to Somerset last Thursday. About 80 miles each way. I used the motorway (60 to 75 mph) for the outward trip, slight headwind and the computer said 60 mpg. I used the A361 for the return home (30 to 60 mph depending on traffic and speed limits) and the computer showed 66 mpg. Based on my previous observations I would deduct 5 mpg to get real values.
Title: Re: MPG for those interested.
Post by: dfconnolly on April 04, 2016, 06:15:35 PM
The only way to get meaningfull mpg figures is to measure the miles recorded between fill ups against the actual fuel put in as measured at the pump.

I find the computer readout on my Hubrid is generally optimistic by at least 4mpg

Regards

Dave C
Title: Re: MPG for those interested.
Post by: Downsizer on April 20, 2016, 11:04:49 AM
I've just completed a 3 day trip from Suffolk to York to Salford and return, a total of 460 miles and I was surprised to be able to complete it on one tankful (of ASDA 95).  It was 95% on dual carriageway (A14/A1/A64/M62) using cruise control on 68 mph wherever possible.  The average speed was 54 mph and there was one blob left on the fuel gauge bar chart when I got back (but only 4 miles left apparently!).  The refill took 36.7 litres giving 12.5 miles per litre or 57.0 mpg.  The trip meter showed 60.4 mpg.  The combination of CVT and cruise control is clearly more frugal than my right foot.
Title: Re: MPG for those interested.
Post by: jazzeck on April 23, 2016, 08:38:38 PM
Certainly agree with dfconnolly on only using actual miles and fuel added, I have studiously (because I have time) recorded fuel consumption this way for my last 5 Honda cars, 2 Civics, 1 Accord 2 Jazzes and will do so for my new Jazz - to be delivered on 19th May. In all cases where fitted the on board consumption optimistic by about 4mpg.
Title: Re: MPG for those interested.
Post by: jazzeck on April 25, 2016, 12:37:52 PM
Also for mk2 EX average mpg for 18370 miles is 45.2.
My wife's mk 2 ES average mpg for 30493 miles is 47.1
Title: Re: MPG for those interested.
Post by: AlanTR on May 22, 2016, 06:08:21 PM
Only owned our 2016 SE CVT for a few weeks but we have recently driven from Tyneside to Cornwall, Devon, Dorset and back - about 8 days and 1200+ miles - averaged 54.9 mpg (trip computer) which seems OK assuming that it's reasonably accurate.

Our previous diesel car, a Hyundai IX20 1.4 CRDi, based on previous experience, would have probably done the same trip at around 56 mpg, so I'm quite impressed with the petrol Jazz. 
Title: Re: MPG for those interested.
Post by: VicW on May 22, 2016, 07:21:05 PM
Alan, your 54.9mpg is probably about 52mpg actual if most trip computer readings are anything to go by. My 2011 CVT in which I do almost no short journeys, records about 51mpg computer mpg which is 48mpg actual.

Vic.
Title: Re: MPG for those interested.
Post by: AlanTR on May 24, 2016, 07:37:48 PM
Thanks for the info - I expected the trip accuracy to be around +/- 5%. So, I'm happy as 52 mpg is also quite good for a petrol car. Great little car....!
Title: Re: MPG for those interested.
Post by: John Ratsey on May 25, 2016, 09:15:22 PM
The computer on my Jazz is reading about 10% optimistic based on >3,000 miles. My previous Jazzes were less optimistic and I have to wonder whether Honda is trying to create an illusion of significantly improved mpg when, in reality, the difference is more modest.

I've just been to, around and from Cornwall and the average of 2 fill-ups was 56.1 mpg (based on litres and miles). A good mixture of driving ranging from motorway to country lanes.
Title: Re: MPG for those interested.
Post by: Downsizer on June 03, 2016, 06:39:24 PM
I've had the car (SE cvt) for 3 months now, and completed 3149 miles of mixed motoring (35 mph average) on 281.7 litres of supermarket RON 95 fuel.  This gives 50.8 mpg, compared to 46.1 for a similar pattern of motoring in my previous 1.4 Mk2 manual.  I'm very happy with this 10% improvement.

Quote from John Ratsey in the Mk2 thread in February:"I think a fair target would be around 10% improvement. The auto idle stop will save a bit of fuel under stop-start driving, the Mk 3 has slightlly better aerodynamics which helps the open road mpg, plus there are tweaks to the engine and its management system."
Title: Re: MPG for those interested.
Post by: andruec on June 20, 2016, 09:48:52 AM
During my 20 mile commute (extra urban with 2 miles urban) it's settled down to around 50mpg.

On a drive back from North Wales (180 miles, steady 60 all the way) it managed 67mpg.
Title: Re: MPG for those interested.
Post by: mikebore on June 20, 2016, 09:55:42 AM
During my 20 mile commute (extra urban with 2 miles urban) it's settled down to around 50mpg.

On a drive back from North Wales (180 miles, steady 60 all the way) it managed 67mpg.

Thanks....is that as displayed in the car info screens, or calculated from tank input? About 3 mpg different as far as I can tell so far.
Title: Re: MPG for those interested.
Post by: John Ratsey on June 20, 2016, 10:33:13 AM
Thanks....is that as displayed in the car info screens, or calculated from tank input? About 3 mpg different as far as I can tell so far.
The average difference between computer and fuel pump is around 9% on my Mk 3. At the last refill the car claimed 60.8mpg but it was 55mpg according to the pump. The best mpg so far (60.5 mpg @ pump) was when the car was nearly new and I was being gentle with the right foot.
Title: Re: MPG for those interested.
Post by: andruec on June 20, 2016, 11:21:18 AM
During my 20 mile commute (extra urban with 2 miles urban) it's settled down to around 50mpg.

On a drive back from North Wales (180 miles, steady 60 all the way) it managed 67mpg.

Thanks....is that as displayed in the car info screens, or calculated from tank input? About 3 mpg different as far as I can tell so far.
As calculated by me, fill to fill. The display settles on 51.7 for the commute and was showing 64mpg for the long drive home. This is my third Jazz and it's unusual for the dash display to under read.

We seem to have a longer range with the Mk3. Previous Jazz put the orange light on for me at around 340 miles driven. This one doesn't do it until about 420 miles. After my drive home from N. Wales I did a week's commuting before filling up and frankly could probably have got another week done if I didn't mind driving Friday with the orange light on.
Title: Re: MPG for those interested.
Post by: John Ratsey on June 20, 2016, 05:23:59 PM
The range may be slightly longer but the main difference is that the trigger for the low fuel warning is not as conservative as on the previous Jazzes. The fuel gauge seems to be reasonably linear with one segment representing two litres.
Title: Re: MPG for those interested.
Post by: andruec on June 20, 2016, 06:31:39 PM
The range may be slightly longer but the main difference is that the trigger for the low fuel warning is not as conservative as on the previous Jazzes. The fuel gauge seems to be reasonably linear with one segment representing two litres.
Oh, I see! Yeah the Mk2 was ludicrous with its warning light.

Mind you I preferred its fuel gauge. This new one is a little inconspicuous.
Title: Re: MPG for those interested.
Post by: jazzeck on June 23, 2016, 05:34:01 PM
two fills now average 50.2mpg vs Mk2  45.2 i.e 11.1%
Ullage from warning light at 26 miles remaining calculated to be actual of 63 remaining, comparable to Mk2.
Range to empty could be 444 on small sample so far as opposed to 418 with Mk2, so smaller tank to save weight may be justified!!
Title: Re: MPG for those interested.
Post by: mikebore on June 29, 2016, 10:46:11 PM
Now done 900 miles in new CVT Mk3 with average 48.2 mpg (tank fill method)

Very happy with this 11% improvement over my CVT Mk2, very similar usage.

Question: how much improvement have owners of new cars seen as the engine runs in/loosens up?

Thanks
Title: Re: MPG for those interested.
Post by: John Ratsey on July 04, 2016, 06:15:22 PM
Leisurely journey from southern England to Scotland - mixture of motorway, A and B roads: Filled up when the car said 2 miles remaining and 1 bar on fuel gauge (the warning light came on with reported 35 miles remaining and 2 bars on the gauge). I managed to get 36.78 litres into the tank which indicated 504 miles at 62.3 mpg. Probably helped by the prevailing SW wind. I'll give an update when the whole trip is finished.
Title: Re: MPG for those interested.
Post by: John Ratsey on July 09, 2016, 09:03:56 PM
1483 miles travelled, 107.3 lites used = 62.8 mpg by my reckoning (the car claimed 67.4 mpg). Leisurely, not fast driving - it was a holiday! For comparison, my Jazz hybrid's first trip to Scotland averaged 65.8 mpg. However, this latest trip had more than its fair share of headwind. The light breeze which might have assisted the car while travelling north was a noticeable headwind when coming south.

Title: Re: MPG for those interested.
Post by: andruec on July 12, 2016, 09:35:39 AM
As calculated by me, fill to fill. The display settles on 51.7 for the commute and was showing 64mpg for the long drive home. This is my third Jazz and it's unusual for the dash display to under read.
Actually this has improved. Probably due to the warmer weather (hah!) but the dash is now showing over 53mpg most of the time and fill-to-fill I'm getting 52mpg.
Title: Re: MPG for those interested.
Post by: KentEx on September 07, 2016, 07:12:49 AM
Hi Alan,
I'm in a similar position to you I suppose. I collected my Ex CVT (2016 model) only last week. The first tank full already used realised 47.8mpg that was both in town and open road driving. I must confess I was expecting a little better, but hey its new and we are still getting used to each other. My previous Jazz (also bought from new) took about 500miles before it ended up delivering a decent return on mpg.
Title: Re: MPG for those interested.
Post by: mikebore on September 07, 2016, 07:23:32 AM
Actually this has improved. Probably due to the warmer weather (hah!) but the dash is now showing over 53mpg most of the time and fill-to-fill I'm getting 52mpg.

That is a much closer match than I get. My fill-to-fill actual was only 2 mpg less than dash on one tankful, but usually about 4 mpg.

I try and be consistent when filling up. I stop filling at first pump shut off, then one more squeeze to second pump shut off. But I fill up at a big variety of places so there may be some variability in how full each tankful really is.

My car has averaged 47.1 mpg over its first 3500 miles. This includes 800 miles with a roof box, running in, and my usual mixture of long and short drives. I do not drive for economy. Best actual fill to fill was 51.5 mpg.

47.1 mpg is 9% better than the overall average I had from my Mk2's 43.3 mpg, except I didn't have the Mk 2 from new, so no running in period.

I am hopeful it will settle down a bit better than 47.1mpg with the running in out of the way.
Title: Improve MPG?
Post by: KJazz on September 08, 2016, 06:44:06 PM
Hello All.  I don't really trust my on board MPG estimate and prefer to make note of mileage and litres. I fill the tank, make note of the numbers, take it close to empty (but never empty), fill it again.  I get about 43-53 MPG depending on how I drove through the last tank.  Not bad for a 2003 Jazz but I would like a bit more. 

Outside of careful steady driving, is there any way to improve the MPG?
Title: Re: MPG for those interested.
Post by: VicW on September 08, 2016, 07:42:56 PM
One way to improve mpg is to anticipate the need to slow down so that you shut the throttle rather than brake.
Example, ahead you see a reduction in speed limit sign. Don't rush up to it and brake down to the new speed, shut the throttle a couple of hundred yards before the sign and slow down. Time lost is negligible.
The same applies to slowing traffic ahead of you.
Look further ahead than the car in front and you will be able to anticipate more the speed of the traffic and potential hazards ahead and adjust your speed accordingly before having to brake.
Unnecessary braking burns fuel.

Vic.
Title: Re: MPG for those interested.
Post by: andruec on September 13, 2016, 04:32:48 PM
Quite right, Vic. I often like to use this link (http://ecomodder.com/blog/hypermiling-101-driving-without-brakes/).

As for MPG - on a recent trip up to see my Dad I managed to get the dash display showing 78.8 mpg at the end of the Stafford/M6 roadworks. I wish they'd been ten miles longer as I might have got it to show 80 :)

Fill-to-fill after the journey back came to 67.4 with a final dash display of - I think - 68.4.

That was 190 miles each way almost all of it at 60mph (50pmh through those roadworks) on cruise control.
Title: Re: MPG for those interested.
Post by: Downsizer on September 28, 2016, 04:41:30 PM
6612 miles completed in 7 months in an SE cvt, with 586.7 litres of supermarket RON 95 bought.  This gives 11.27 mpl or 51.23 mpg.  Trip B, running throughout, shows 35 mph and 56.1 mpg, flattering the consumption by nearly 10%.
Title: Re: MPG for those interested.
Post by: ColinB on September 29, 2016, 08:43:15 AM
There seems to be a view on here that the computer's MPG read-out is less accurate than the manual fill-to-fill method. Can anyone suggest why that might be ? The computer must have access to accurate data about fuel flow rates (if it didn't, the engine probably wouldn't run well) and distance travelled (for legal reasons), so surely the MPG calculation ought to be fairly accurate ... so what's going wrong ? What are the likely sources of error in the instrumentation or the calculation that can result in an error of around 10% ? And are there any legal requirements (maybe in the Construction & Use Rules ?) about the accuracy of the calculation ? Just wondering.
Title: Re: MPG for those interested.
Post by: andruec on September 29, 2016, 09:04:10 AM
There seems to be a view on here that the computer's MPG read-out is less accurate than the manual fill-to-fill method. Can anyone suggest why that might be ?
They always are.

https://www.google.co.uk/search?q=why+car+mpg+display+wrong&rlz=1C1CHBF_en-GBGB704GB704&oq=why+car+mpg+display+wrong&aqs=chrome..69i57.5534j0j7&sourceid=chrome&ie=UTF-8#q=car+mpg+display+wrong (https://www.google.co.uk/search?q=why+car+mpg+display+wrong&rlz=1C1CHBF_en-GBGB704GB704&oq=why+car+mpg+display+wrong&aqs=chrome..69i57.5534j0j7&sourceid=chrome&ie=UTF-8#q=car+mpg+display+wrong)

 :)

Or for a simpler explanation:

https://www.youtube.com/watch?v=cOeKidp-iWo (https://www.youtube.com/watch?v=cOeKidp-iWo)

 :D

Even fill-to-fill isn't without issues. Using a different pump, different temperature. I also question how quickly the figure drops when you first use the vehicle from cold. Like last weekend. I was down to the last few litres. Car had done normal trips for a couple of weeks. You'd think the display had pretty much settled down to an average.

Yet within a minute of me setting off from work it had dropped from a tad under 57 mpg to 51 mpg. How can the mpg after driving half a mile affect the average mpg calculated over 400 miles by that amount?
Title: Re: MPG for those interested.
Post by: ColinB on September 29, 2016, 09:43:05 AM
There seems to be a view on here that the computer's MPG read-out is less accurate than the manual fill-to-fill method. Can anyone suggest why that might be ?
They always are.
There's usually a reason (or reasons) for this kind of thing so I was trying to see whether anyone could explain. Some useful stuff in that blog, although it seems to me that some of those factors affect the manual method as well (eg thermal expansion of the tank), so we probably shouldn't consider either method as 100% accurate.
Title: Re: MPG for those interested.
Post by: ColinS on September 29, 2016, 01:39:54 PM
The simple fact is that it is illegal for the speedometer to read low, therefore all manufacturers calibrate them to read high.  Everything is linked to that, including the odometer, so the MPG computer calculation is artificially low.

Petrol pumps are covered by "weights and measures" in the UK and are therefore accurate.

Believe the pump not the car.
Title: Re: MPG for those interested.
Post by: mikebore on September 29, 2016, 04:46:51 PM
I understand about legal requirement for speedometer not to read low, but surely that is not true for the odometer, which is what the car computer uses for the calculated mpg.

If the odometer was also wrong it would affect the manual tank fill method too.
Title: Re: MPG for those interested.
Post by: andruec on September 29, 2016, 04:50:01 PM
If the odometer was also wrong it would affect the manual tank fill method too.
Tyre diameters reduce as they wear so any measurement derived from wheel rotation is inevitably going to be inaccurate ;)

MPG could be accurate with respect to the odometer but never accurate with respect to miles actually driven.
Title: Re: MPG for those interested.
Post by: mikebore on September 29, 2016, 05:56:38 PM
I don't believe my odometer is 10% wrong to true miles, which is what is implied by suggestion that the discrepancy is due to the legal requirement for displayed mph.
Title: Re: MPG for those interested.
Post by: Skyrider on September 29, 2016, 07:02:43 PM
I really don't care about fuel consumption to the nearest egg cup full to the mile. My Jazz does about 100 miles per 1/4 tank of fuel around town, more on the motorway, a bit more on the first quarter tank due to the long filler pipe full being added. What is the big deal (obsession) about absolute accuracy? it will never be achieved on the road.
Title: Re: MPG for those interested.
Post by: VicW on September 29, 2016, 07:22:30 PM
Deeps +1

Vic.
Title: Re: MPG for those interested.
Post by: Skyrider on September 29, 2016, 08:05:26 PM
Deeps +1

Vic.

Fuel gauge OCD?  ;)
Title: Re: MPG for those interested.
Post by: culzean on September 29, 2016, 08:36:56 PM
Deeps +1

Vic.ln

Fuel gauge OCD?  ;)

"Because life's too short"
Title: Re: MPG for those interested.
Post by: Downsizer on September 29, 2016, 10:25:23 PM
I've always monitored actual (pump-based) consumption because a significant change could suggest something wrong with the car.  I only reported the trip computer variance out of interest.  I think the difference originates in the way the fuel use is measured rather than any odometer error.
Title: Re: MPG for those interested.
Post by: KentEx on September 30, 2016, 06:59:24 AM
Deeps - I'm with you 100%
We all want I suppose the best economy, but to insist on pin point accuracy is just a complete unnecessary mind bender. The instruments are for guidance and if they are within +/- 10%, that's good enough for me. Too many other things in life to get us worked up about and stressed out. Where we should be concerned is where there is a dramatic change.
Lets get on with driving!
Title: Re: MPG for those interested.
Post by: ColinS on September 30, 2016, 07:46:57 AM
I don't believe my odometer is 10% wrong to true miles, which is what is implied by suggestion that the discrepancy is due to the legal requirement for displayed mph.
Thinking about it, logically you must be correct on this.  Like Deeps, I'm not bothered by it, but it definitely reads higher on the computer than actual MPG.  My last CRV was exactly the same.
Title: Re: MPG for those interested.
Post by: ColinB on September 30, 2016, 08:35:21 AM
There's clearly a group of folks who aren't particularly concerned about MPG and how it's calculated and I respect that. But the thread title is "MPG for those interested" and a number of other people who posted earlier clearly are interested, so perhaps I could respectfully ask those who aren't interested to allow that discussion to continue please ?

For me, I'm just interested in whether anyone can put up any plausible theories as to why two methods of measuring the same thing produce significantly different results. Doesn't mean I'm anal about the last fraction of an MPG, it's just an objective academic interest (call it an enquiring mind). I don't buy the "That's just the way it is" theory, there's got to be some underlying reasons. And some of the reasons suggested so far may also affect the supposedly accurate manual fill method ... which my sad mind finds quite interesting.
Title: Re: MPG for those interested.
Post by: Skyrider on September 30, 2016, 09:22:47 AM
At least I prompted a few new posts on a very quiet forum.  ;)
Title: Re: MPG for those interested.
Post by: culzean on September 30, 2016, 09:43:46 AM
I haven't done this for a while, but found that if I drove consistently and smoothly the mpg display is closer to my calculation from actual fuel used, it is more accurate to take average from figure without too many 'spikes' from high fuel usage (hills and acceleration) in it - your car computer uses injector open time to get amount of fuel used, and miles travelled from odometer which uses same signal as speedometer (which by law reads high rather than low). It samples these figures every so often (seems to be 10 seconds from the way mpg readout changes) it uses values from this instantaneous snapshot to calculate 'average' mpg.  There is also a theory that car makers want reading to be high, Honda are by no means the worst for accuracy, some cars read up to 20% optimistic.


I guess periods of coasting  / steady driving last longer and happen more often than bursts of acceleration and sampling time is much more likely to catch them, which may skew figure upwards.
Title: Re: MPG for those interested.
Post by: Skyrider on September 30, 2016, 10:48:29 AM
I know that one of my diesel cars used injector open time for fuel use calculations. As the ECU already has this information the only other fuel metering device required is your right foot. Green lights alongside the speedometer = car in granny mode, more right foot effort required!
Title: Re: MPG for those interested.
Post by: ColinS on September 30, 2016, 11:08:30 AM
So I found this:

"Modern engines are controlled by computers that calculate how many microliters of fuel to inject into each cylinder per combustion cycle. To determine fuel efficiency, the computer keeps a running total of both the fuel delivered to the engine and the distance driven."

"Honda uses additional inputs to calculate trip mpg. “We look at the fuel-consumed data that comes from the engine-control computer, but we also track the float sensor measuring the fuel level in the tank,” says Raj Manakkal, chief engineer for electrical and infotainment devices. He also points out that, due to temperature changes, plastic fuel tanks can expand and contract by as much as a liter. On the Acura ILX, that yields a total variation of 4 percent."
Title: Re: MPG for those interested.
Post by: Skyrider on September 30, 2016, 05:27:26 PM
So I found this:

 says Raj Manakkal, chief engineer for electrical and infotainment devices.

Fuel consumption and infotainment, hmmm. Now I see the trip A history fault link. My car gets the fix next week.
Title: Re: MPG for those interested.
Post by: John Ratsey on October 02, 2016, 07:47:30 AM
My own concern is that Honda has consciously tweaked the software to overstate the mpg so that owners are mislead into thinking their car is giving better mpg than the reality and hence closer to the advertised values. (Most likely other manufacturers do the same). My Mk 3 is nearer 10% than 5% optimistic.

It has to be a different part of the software to that which triggers the low fuel warning which effectively understates the mpg.
Title: Re: MPG for those interested.
Post by: ColinB on October 02, 2016, 09:59:18 AM
My own concern is that Honda has consciously tweaked the software to overstate the mpg...
Hence my question:
... are there any legal requirements (maybe in the Construction & Use Rules ?) about the accuracy of the calculation ?
My amateur trawl through Google didn't find anything; there's plenty about the Official figures, and about display of energy efficiency labels, but nothing I can find about on-board display. And sadly, as we know from the VW debacle, manufacturers are not averse to looking for innovative ways of making their cars look good if there's no rule actually preventing it. My suspicion is that the software has to make a number of detailed assumptions (fuel temperature, density, calorific value, etc) in it's calculations, and it's probably programmed to take the most optimistic assumptions which build to a cumulative "good picture" for display purposes.

Does it matter ? The need for accuracy of the displayed MPG really depends on what use we make of it. My personal view is that it's not for comparison with some theoretical optimum or "Official" value, but to monitor the car for faults that might show up with a change in MPG and/or to improve our own energy-efficient driving style. For those purposes the displayed value is perfectly adequate even with known errors, and is more immediately obvious to the driver than the (probably) more accurate tank-fill method.
Title: Re: MPG for those interested.
Post by: TG on October 02, 2016, 05:16:51 PM
As a school technology project, we tried to measure fuel flow as a way of estimating instant mpg. This seemed quite simple without a high pressure fuel circuit and electronic ignition on a basic carburetor/points car, but the flow rate was too low for our simple vane driven flow meter and pretty much impossible these days. 

Modern road cars are at ~30% fuel efficiency, current F1 engines are running at 47% (up from ~40% since the turbo was reintroduced), principally by better understanding of ultra-lean fuel chemistry and the use of a pre-combustion chamber (Turbulent Jet Ignition - TJI).  This seems to originally have been a Cosworth concept that has moved to Ferrari, Mercedes and Renault - no mention of Honda yet (although it sounds similar to their 1970s CVCC engine).
 
The TJI system Mahle outlines incorporates a small pre-chamber in which the injector and the spark plug reside. The injection is made at around 60-deg before the piston has reached top-dead-centre. 97% of the fuel energy goes into the main combustion chamber, with the remaining 3% in this small pre-chamber. A nozzle between the pre-chamber and the main chamber has a series of tiny holes, presenting the mix to the main chamber in a series of high-pressure jets. The spark arrives in the pre-chamber at around 22-deg before top-dead centre (BTDC) and that igniting mass is allowed into the main combustion chamber at between 12 and 5-degrees BTDC – thereby igniting the fuel within the main chamber.  ....  only the mix within the small chamber needs to be relatively rich; that in the main chamber – because it will be ignited by the already sparked fuel mixture released from the pre-chamber – can be much weaker (ie less fuel, more air) than it would otherwise need to be to avoid detonation, by as much as 20%. The further you can push the detonation limit, the bigger the bang you can safely produce and therefore the power output increases.  ....  The trick here is that the air-fuel mixture is pre-ignited in a pre-chamber around the spark plug. This results in the formation of plasma jets that reach the piston primarily at the outer edge and ignite the remainder of the mixture. While ignition normally takes place in the centre of the cylinder, with Mahle Jet Ignition it essentially takes place from the outside toward the inside. This allows significantly better combustion of the fuel mixture. The result: more power with considerably less residue.

(http://msmproduction.s3-eu-west-1.amazonaws.com/s3fs-public/content/MArk%20Hughes/mahle.jpg)

http://www.motorsportmagazine.com/opinion/f1/ferraris-formula-1-jet-ignition (http://www.motorsportmagazine.com/opinion/f1/ferraris-formula-1-jet-ignition)
--
TG
Title: Re: MPG for those interested.
Post by: KentEx on October 03, 2016, 07:41:52 AM


Does it matter ? The need for accuracy of the displayed MPG really depends on what use we make of it. My personal view is that it's not for comparison with some theoretical optimum or "Official" value, but to monitor the car for faults that might show up with a change in MPG and/or to improve our own energy-efficient driving style. For those purposes the displayed value is perfectly adequate even with known errors, and is more immediately obvious to the driver than the (probably) more accurate tank-fill method.
[/quote]

Spot on Colin ....
Recent long trip recorded 56.5mpg, 2 up + boot full.of luggage.
This compared to previous trip of 57.2mpg - pretty consistent return.

KentEx
Title: Re: MPG for those interested.
Post by: Skyrider on October 04, 2016, 11:49:52 AM


Does it matter ? The need for accuracy of the displayed MPG really depends on what use we make of it. My personal view is that it's not for comparison with some theoretical optimum or "Official" value, but to monitor the car for faults that might show up with a change in MPG and/or to improve our own energy-efficient driving style. For those purposes the displayed value is perfectly adequate even with known errors, and is more immediately obvious to the driver than the (probably) more accurate tank-fill method.

Spot on Colin ....
Recent long trip recorded 56.5mpg, 2 up + boot full.of luggage.
This compared to previous trip of 57.2mpg - pretty consistent return.

KentEx
[/quote]

I also agree, I use it purely as a comparison  to monitor the cars health and well being. The actual figures are just part of the marketing and customer pleasing waffle.
Title: Re: MPG for those interested.
Post by: mikebore on October 04, 2016, 12:16:06 PM
Does it matter ? The need for accuracy of the displayed MPG really depends on what use we make of it. My personal view is that it's not for comparison with some theoretical optimum or "Official" value, but to monitor the car for faults that might show up with a change in MPG and/or to improve our own energy-efficient driving style. For those purposes the displayed value is perfectly adequate even with known errors, and is more immediately obvious to the driver than the (probably) more accurate tank-fill method.

Colin, I think you are making a virtue out of necessity.!

I would turn round what you have said, and say "because it is so inaccurate it is only useful for monitoring the car for faults that might show up with a change in MPG and/or to improve our own energy-efficient driving style.

I like to keep records of all the cars I have owned for comparison. If it was accurate I wouldn't bother keeping tank fill manual records.
Title: Re: MPG for those interested.
Post by: Skyrider on October 04, 2016, 12:55:19 PM
What cars have you owned that have had totally accurate mpg readout and how did you know they were accurate?
Title: Re: MPG for those interested.
Post by: mikebore on October 04, 2016, 01:39:51 PM
What cars have you owned that have had totally accurate mpg readout and how did you know they were accurate?

I didn't mean to imply that any of the others were accurate, but you're quite right, I probably wouldn't stop keeping manual records even if the Jazz was more accurate.

I have only owned five cars which calculated MPG: Hondas Mk 1, Mk2, Mk3, and Fords Focus and Mondeo. Of these the Mondeo was the most accurate, nearly dead on. The Mk 3 is the least accurate.
Title: Re: MPG for those interested.
Post by: andruec on October 14, 2016, 05:22:20 PM
402 miles driven. 12 miles remaining (according to car). Orange light on. 35 litres to full.

So that's about 52mpg and suggests that the 12 miles remaining was a bit pessimistic.
Title: Re: MPG for those interested.
Post by: culzean on October 14, 2016, 06:46:28 PM
402 miles driven. 12 miles remaining (according to car). Orange light on. 35 litres to full.

So that's about 52mpg and suggests that the 12 miles remaining was a bit pessimistic.

When 'miles remaining' is '0' you are going on to reserve which from experience and other posters is at least 5 to 6 litres.  Some cars give virtually no warning - I think Fiat 500 and BMW Mini are amongst the worst,  giving less than 20 miles when fuel light clicks on. In todays world of bigger petrol stations that are further apart (just like hospitals) I think you need all the warning you can get,  most of the petrol stations on my satnav have ceased trading and I am not surprised - there is not much profit for station owners in selling fuel,  that's why most now have a shop attached and sell coffee etc.
Title: Re: MPG for those interested.
Post by: Skyrider on October 14, 2016, 07:30:00 PM
I think you need all the warning you can get,

My car has a fuel gauge, it gives plenty of warning that the fuel level is getting low.
Title: Re: MPG for those interested.
Post by: ColinB on October 14, 2016, 07:50:16 PM
12 miles remaining (according to car).
I wouldn't trust the computer's "miles remaining" at all. It was discussed here:
http://clubjazz.org/forum/index.php?topic=8559.0 (http://clubjazz.org/forum/index.php?topic=8559.0)
12 miles seems to be much less than the possible error in the calculation.
Title: Re: MPG for those interested.
Post by: DaveBerks on October 24, 2016, 10:33:03 AM
600 miles on the clock since new so not run-in yet. Computer says average mpg of 51. Mix of town and motorway driving. Very pleased as my previous car (a 2005 Corolla) did 37mpg average.
Title: Re: MPG for those interested.
Post by: 14hondas on October 29, 2016, 08:47:36 PM
3778 miles, 49.7mpg (10.94/ltre).

This is 4.53mpg better than Mk2 traded in
Title: Re: MPG for those interested.
Post by: Skyrider on October 29, 2016, 08:54:10 PM
3778 miles, 49.7mpg (10.94/ltre).

This is 4.53mpg better than Mk2 traded in

The 49 ish mpg is what I get. Ish is accurate enough for me.
Title: Re: MPG for those interested.
Post by: andruec on October 29, 2016, 09:18:12 PM
Now that summer is over mine has dropped a little. My typical drive is a commute between Brackley and Banbury. 10 miles of country A-road at 50mph. 2 miles of town driving which is a bit stop start in the evening. I'm managing 52mpg pump to pump at the moment. The car is claiming 55mpg :-/

I'm hopeful that I might keep things above 50mpg over winter but it's far from certain. Banbury evening rush hour becomes particularly bad over the Christmas period. Quite why people feel the need to be travelling to/from the shops at 5pm for the last half of December is beyond me. Why not shop earlier in the day? Come to that why even bother with shops - I buy everything online.
Title: Re: MPG for those interested.
Post by: Skyrider on October 29, 2016, 09:24:37 PM
My car lies, it says 53, but does 49.
Title: Re: MPG for those interested.
Post by: John Ratsey on November 04, 2016, 05:15:56 PM
My Orange Jazz 1.3 SE CVT was traded in last week for an HR-V SE CVT. The Jazz managed 57.8 mpg over 5300 miles of mainly open road driving. The mpg given by the computer averaged 8.8% higher (ie abut 62.9 mpg) with the difference ranging between 6% and 11% higher than the value indicated by fuel bought and miles travelled (I noted the computer mpg at each fill-up). I hope the HR-V will manage about 50mpg under similar conditions.

My previous Jazz (hybrid) managed 58.8 mpg over nearly 16,000 miles of similar driving conditions to that incurred by the Mk 3 which confirmed my suspicion that, for my normal driving, the hybrid system didn't provide much benefit although I would expect a Mk 3 hybrid to do better than the Mk 2 with the motor supplementing the Atkinson cycle end of the revs providing some useful extra torque and reduce the need for the petrol engine to put on the revs.
Title: Re: MPG for those interested.
Post by: Kenneve on November 10, 2016, 10:55:49 AM
Hi Guys

Attached is the latest Trip A Screen which is showing my fuel consumption for just over 1000 miles
I am quite happy with the results, whilst accepting the few % optimistic figures.
My Mk2 EX CVT never got anywhere near those figures on a consistent basis.

I note on a previous post someone was suggesting the a larger fuel tank was needed, Why? just how many many miles is acceptable on a full tank, in my view 400-450 miles is adequate. Why tow around unnecessary weight?
Title: Re: MPG for those interested.
Post by: trebor1652 on November 20, 2016, 11:16:48 AM
I ended up pushing things the other day, fuel gauge said low fuel and by the time I found an open petrol station the car had done some 30 miles from the readout indicating 0 miles left.
Filled up with 39.7 litres, much to close to being a disaster (40 litre tank) never in 50 years of driving have I been that close to "running dry".

Sent from my XT1039 using Tapatalk

Title: Re: MPG for those interested.
Post by: culzean on November 20, 2016, 11:34:07 AM
I ended up pushing things the other day, fuel gauge said low fuel and by the time I found an open petrol station the car had done some 30 miles from the readout indicating 0 miles left.
Filled up with 39.7 litres, much to close to being a disaster (40 litre tank) never in 50 years of driving have I been that close to "running dry".

Did you do it on purpose as a test ?  If I was doing that I would have a couple of 5 litre cans in the boot,  the Jazz doesn't look like a heavy car but just try 'pushing' one for real LOL

Never knowingly let my tank get below 1/4 full (or 3/4 empty if you are a pessimist).
Title: Re: MPG for those interested.
Post by: trebor1652 on November 20, 2016, 11:37:27 AM
It was just circumstances, I normally fill before the low fuel lights up.

Sent from my XT1039 using Tapatalk

Title: Re: MPG for those interested.
Post by: John Ratsey on November 20, 2016, 12:20:14 PM
I ended up pushing things the other day, fuel gauge said low fuel and by the time I found an open petrol station the car had done some 30 miles from the readout indicating 0 miles left.
Filled up with 39.7 litres, much to close to being a disaster (40 litre tank) never in 50 years of driving have I been that close to "running dry".
Do you stop filling at the first cut-out of the pump or keep trying and fill up the filler pipe (my usual technique)? I'm sure the pipe holds another litre or two which probably explains why it's often 50 miles or more before the fuel gauge moves off full. Nonetheless, 39.7 litres is getting close to empty.
Title: Re: MPG for those interested.
Post by: trebor1652 on November 20, 2016, 01:42:46 PM
Yes the pump clicks off and on a couple of times usually, try to squeeze in as much as possible.

Sent from my XT1039 using Tapatalk

Title: Re: MPG for those interested.
Post by: Skyrider on July 02, 2017, 03:04:24 PM
I have just completed a 1,200 mile pensioner roam around. Starting and ending at my home in central Scotland it covered the cotswolds, west country, and London. Always driving at the speed limit, aircon always on, the full to full consumption over the 1,200 miles was 54mpg. The cars info display showed 57mpg. Much was at 70 mph on cruise control, but it included pottering and London traffic. No consideration was given to economic driving, I am impressed.
Title: Re: MPG for those interested.
Post by: andruec on July 02, 2017, 05:29:15 PM
You went into London? What the hell for?

I live in the South Midlands and I've got more sense than to go into that hell hole :)
Title: Re: MPG for those interested.
Post by: Skyrider on July 02, 2017, 05:51:33 PM
You went into London? What the hell for?

I live in the South Midlands and I've got more sense than to go into that hell hole :)

I agree it has become a hell hole, although I have lived in Scotland for over 50 years it is where I was brought up and visit the relatives. It  has changed so much it has become like visiting a foreign country.
Title: Re: MPG for those interested.
Post by: Jocko on July 02, 2017, 06:13:37 PM
I love visiting London, or at least the tourist bits. It has been a few years but I doubt I would go back now.
Title: Re: MPG for those interested.
Post by: Downsizer on July 04, 2017, 05:33:57 PM
I've just run the tank down to 1 mile remaining, to get to my favourite ASDA pumps, and the refill took 39.0 litres to the first stop.  453 miles covered, giving 53 mpg, with the trip meter showing 57. There was still one bar showing on the gauge.  The miles remaining fell quite a bit faster than the actual miles covered during the last 40 miles at 60mph.  I expect there was still another 20 t0 30 miles available.
Title: Re: MPG for those interested.
Post by: mikebore on July 04, 2017, 05:40:21 PM
Some screenshots from my Fuelly page:

No special attempt at maximising MPG.

Stats include occasional roof boxes, bikes on roof etc.

60.2 best was with a following wind from Gower to Derby.
Title: Re: MPG for those interested.
Post by: Jocko on July 04, 2017, 06:06:02 PM
I find Fuelly quite good, as you can select some custom stats.
Here are my details for my MkI GD5.

(http://i914.photobucket.com/albums/ac347/Jocko_2010/Dash_zpskgkljfnd.jpg)

(http://i914.photobucket.com/albums/ac347/Jocko_2010/Details_zpspwvoftdm.jpg)

Title: Re: MPG for those interested.
Post by: mikebore on July 04, 2017, 06:27:27 PM
Jocko, your images aren't working for me...I would be interested to see them if you can make them work. I am seeing message "please update your account to enable third party hosting"

I meant to add in my previous post that the discrepancy between trip computer mpg and tank-to-tank mpg has increased steadily on my car. When it was new the error was 2-3 mpg. Now 12 months 14,000 miles it is 5-6 mpg

Any thoughts on that? rolling radius change as tyres wear? You would think that would feed into both types of mpg.
Title: Re: MPG for those interested.
Post by: Downsizer on July 04, 2017, 07:03:01 PM
I meant to add in my previous post that the discrepancy between trip computer mpg and tank-to-tank mpg has increased steadily on my car. When it was new the error was 2-3 mpg. Now 12 months 14,000 miles it is 5-6 mpg

Any thoughts on that? rolling radius change as tyres wear? You would think that would feed into both types of mpg.
Any change in motoring mix, I.e long runs v short?  I have found the discrepancy to be around 8% pretty consistently.
Title: Re: MPG for those interested.
Post by: Jocko on July 04, 2017, 08:21:01 PM
I'll try something else.
Title: Re: MPG for those interested.
Post by: Jocko on July 04, 2017, 08:25:06 PM
Does this do it?



Title: Re: MPG for those interested.
Post by: mikebore on July 04, 2017, 09:08:48 PM
Yes that works. Impressive!
Title: Re: MPG for those interested.
Post by: mikebore on July 04, 2017, 10:02:32 PM
I'll try something else.

Reckon you were hit by this:
http://www.bbc.co.uk/news/technology-40492668 (http://www.bbc.co.uk/news/technology-40492668)
Title: Re: MPG for those interested.
Post by: Jocko on July 04, 2017, 10:57:40 PM
That'll be it. I'll delete my images from Photobucket and post them elsewhere.
Title: Re: MPG for those interested.
Post by: TG on July 05, 2017, 12:44:43 AM
Four hundred dollars Photobucket?  I think I'll update my wheel bearings post to use imgur or tinypic (and not use Clubjazz bandwidth)
--
TG
Title: Re: MPG for those interested.
Post by: mikebore on July 05, 2017, 06:06:38 AM
I meant to add in my previous post that the discrepancy between trip computer mpg and tank-to-tank mpg has increased steadily on my car. When it was new the error was 2-3 mpg. Now 12 months 14,000 miles it is 5-6 mpg

Any thoughts on that? rolling radius change as tyres wear? You would think that would feed into both types of mpg.
Any change in motoring mix, I.e long runs v short?  I have found the discrepancy to be around 8% pretty consistently.

No, no correlation with type of journeys. I approximately alternate 97 and 95 RON fuel, but that doesn't seems to be a factor either.

I have not recorded the trip computer mpg, just eyeballed it as I enter the pump data in Fuelly, but I will start doing so.
Title: Re: MPG for those interested.
Post by: culzean on July 05, 2017, 11:13:16 AM
I approximately alternate 97 and 95 RON fuel, but that doesn't seems to be a factor either.

If you say you are not getting any extra MPG from 97RON then it is cheaper to buy Redex and use that to keep system clean,  I did notice better performance or MPG improved* by up to 10% on 97,  but you can't have both because when the engine feels livelier it is a hard choice to drive like a nun.

(* and that improvement was on identical 80 mile return daily commute on basically alternate weeks of 95 and 97 , covering years so IMHO is valid and takes allowance for different weather and traffic conditions)
Title: Re: MPG for those interested.
Post by: Downsizer on July 05, 2017, 12:26:59 PM
If you say you are not getting any extra MPG from 97RON then it is cheaper to buy Redex and use that to keep system clean,  I did notice better performance or MPG improved* by up to 10% on 97
I'm afraid I'm always suspicious of benefits "up to x%"!  I know this has been discussed in some detail previously, but I'm sticking to ASDA 95 and no Redex as the cheapest option.
Title: Re: MPG for those interested.
Post by: culzean on July 05, 2017, 12:50:19 PM
If you say you are not getting any extra MPG from 97RON then it is cheaper to buy Redex and use that to keep system clean,  I did notice better performance or MPG improved* by up to 10% on 97
I'm afraid I'm always suspicious of benefits "up to x%"!  I know this has been discussed in some detail previously, but I'm sticking to ASDA 95 and no Redex as the cheapest option.

It is a bit like someone saying they don't like something when they have never tried it, an untenable position - a bottle of Redex is the cheapest maintenance you will ever do on your car - I have had gummed up carbs that have been like new after a bit of a soak in redex,  and injectors (and fuel system) do get clogged up with gum from the evaporation of dinosaur juice (which is not as pure as it seems).

https://www.youtube.com/watch?v=WQN-0zvZNbY (https://www.youtube.com/watch?v=WQN-0zvZNbY)

There is a note below the video that says the car was run on 95 octane (although it needs 97) for the good reason that 97 contains cleaners that would have done what the redex does and they did not want to cloud the issue.  The redex had by far the biggest effect on the dyno figures for the lowest cost.  and you can't really argue with dyno results as they are done under very controlled conditions to ensure repeatability.

And Asda fuel (or any supermarket fuel with well documented lower levels of additives) may not be the cheapest option if your car is doing less miles per gallon.  I like the American system where supermarkets don't supply fuel but give money off vouchers that can be used at any gas station.
Title: Re: MPG for those interested.
Post by: Jocko on July 05, 2017, 01:04:40 PM
Just watched Jason's video. I'll give it a try. Asda are selling it for £3.00.
Title: Re: MPG for those interested.
Post by: culzean on July 05, 2017, 01:28:01 PM
Just watched Tiff's video. I'll give it a try. Asda are selling it for £3.00.

Anyone who has a shower at home knows how the spray head (like an injector nozzle) gets clogged and sprays less water and in the wrong pattern, and needs a bit of 'limescale remover /de-scaler) every so often to restore its original spray pattern,  think of Redex like that.

If car has never been done before I would put an overdose in to see results more quickly - it certainly will not do any harm. 
Title: Re: MPG for those interested.
Post by: Hobo on July 05, 2017, 02:37:53 PM

And Asda fuel (or any supermarket fuel with well documented lower levels of additives) may not be the cheapest option if your car is doing less miles per gallon.

Rubbish, I used to work for Texaco and fuel we supplied to supermarkets had exactly the same additives as our own petrol stations, also petrol at the refineries was supplied with the same additives to all supermarkets and major petrol companies tankers.

Redex was used many years ago to reduce build up of carbon when vehicles used to get carbon from leaded petrol and needed decoking but is completely unnecessary in modern engines.
Title: Re: MPG for those interested.
Post by: culzean on July 05, 2017, 02:51:58 PM
Try telling my carbed motorbikes and lawnmower that redex doesn't work - and obviously the dynomometer was telling porkies as well.

There are postings from tanker drivers on internet that yes, supermarket fuel does get same additives, just less of them as they get added when tanker leaves the depot.  Redex may well remove carbon,  but that is not its main purpose, which is to dissolve petrol deposits, which it does very well.
Title: Re: MPG for those interested.
Post by: Hobo on July 05, 2017, 03:05:36 PM
Try telling my carbed motorbikes and lawnmower that redex doesn't work - and obviously the dynomometer was telling porkies as well.

There are postings from tanker drivers on internet that yes, supermarket fuel does get same additives, just less of them as they get added when tanker leaves the depot.  Redex may well remove carbon, 

Sounds like you have problems with your bikes then, I have ridden and maintained high powered bikes for many many years and never needed to use Redex, you are welcome to your opinions but that is what most are just as your supermarket fuel is theory is wrong.
Title: Re: MPG for those interested.
Post by: Jocko on July 05, 2017, 03:43:54 PM
Well I watched the Fifth Gear video that Culzean linked to, and I am certainly going to spend £3 on a bottle, just in case it does work. Won't do any harm.
Title: Re: MPG for those interested.
Post by: culzean on July 05, 2017, 03:48:15 PM
You just gotta love people who don't  use a product but can confidently tell others that it doesn't work.  IMHO fuel additives and cleaners like redex exist to maintain the parts of your car that you cannot access.  It isn't as though redex is hard to obtain or costs a lot of money, so it won't break the bank for people to to check it out for themselves, it certainly won't do any harm.
Title: Re: MPG for those interested.
Post by: jazzway on July 05, 2017, 04:12:59 PM
@culzean, you are always praising Redex and i have seen the video before and find it very interesting. For a year now i fill the tank with Shell V-Power 98 ethanol for two reasons: there's zero ethanol in the Beligian V-Power and the second reason are the cleaning additives in it.

Yes, V-Power is more expensive, but living against the Belgian border it is there still cheaper than our Dutch Euro95 petrol (with ethanol).
About the Redex... it cleans more than the additives in petrol, but what happens with the dirt it losens? Does it solve and not float to another place? And how would you compare 95 octane petrol (with the 5-10 percent) ethanol plus Redex, to a higher octane petrol without ethanol and better additives (V-Power/BP Ultimate) without Redex?

I have to mention that our Jazz always start at once, drives smooth and quiet, doesn't make weird noises and our MPG (most short trips) are on the left. ;) Also i haven't found a (online) place where i can buy Redex in the Netherlands. There are other brands, but i don't think they are the same.
Title: Re: MPG for those interested.
Post by: Hobo on July 05, 2017, 04:43:45 PM
Just as you have got to love people that set themselves up as an expert on everything and spout about supermarket fuel being inferior to other fuels, for your information and just to correct your assumptions, I have used Redex many years ago on side valve vehicles to reduce the need for decoking and in the days of leaded petrol, but as stated in modern engines it is completely unnecessary and could do more harm than good.
Title: Re: MPG for those interested.
Post by: culzean on July 05, 2017, 05:03:14 PM
About the Redex... it cleans more than the additives in petrol, but what happens with the dirt it losens? Does it solve and not float to another place? And how would you compare 95 octane petrol (with the 5-10 percent) ethanol plus Redex, to a higher octane petrol without ethanol and better additives (V-Power/BP Ultimate) without


If you have been using premium fuel your system will probably be pretty clean anyway, but purpose made system cleaners are not expensive.

Anything that the cleaner dissolves is only stuff that is normally in fuel anyway and will just get injected and burned with fuel.

Redex is not the only cleaner available Wynns, STP and others make similar product,  you only need to use it occasionally, add some to tank of fuel about once every one or two months - which means it is not expensive.
Title: Re: MPG for those interested.
Post by: Kenneve on July 05, 2017, 08:03:11 PM
Going back to around 2003 I recall that I had poor running problems with my car (at the time it was a Landrover Freelander Auto) and complained to the dealer. His response was to ask what fuel i was using, to which i responded Sainsburys.
He immediately suggested that I change fuel to one of the main fuel companies (is this case BP) and see what the difference was.

I was very dubious about the possible result, but I have to say that there was a significant difference ie, much smoother running and better MPG and I have never used supermarket fuel since. OK it was a penny or two dearer, but this was more than offset by the increased MPG, probably in order of 10%, which of course on that vehicle was only 2 or 3 miles different.

So, i'm now on my fourth Jazz, and I still stick with the main petrol companies wherever possible.
I suppose I could be classed as a somewhat spirited driver, however my Mk3 EX CVT has covered almost 7000 miles so far and returned 52.7 MPG on the trip computer, and as long as it stays on the plus side of 50 MPG, I'm happy.
Title: Re: MPG for those interested.
Post by: culzean on July 05, 2017, 08:48:57 PM
Going back to around 2003 I recall that I had poor running problems with my car (at the time it was a Landrover Freelander Auto) and complained to the dealer. His response was to ask what fuel i was using, to which i responded Sainsburys.
He immediately suggested that I change fuel to one of the main fuel companies (is this case BP) and see what the difference was.

I was very dubious about the possible result, but I have to say that there was a significant difference ie, much smoother running and better MPG and I have never used supermarket fuel since. OK it was a penny or two dearer, but this was more than offset by the increased MPG, probably in order of 10%, which of course on that vehicle was only 2 or 3 miles different.

So, i'm now on my fourth Jazz, and I still stick with the main petrol companies wherever possible.
I suppose I could be classed as a somewhat spirited driver, however my Mk3 EX CVT has covered almost 7000 miles so far and returned 52.7 MPG on the trip computer, and as long as it stays on the plus side of 50 MPG, I'm happy.

I had a similar experience,  My wife used to fill up at supermarkets to use her vouchers, I used to drive her  car sometimes  (a 53 plate Jazz GD 1.4 which was identical to mine except colour) and I always thought it didn't feel as smooth or responsive as my Jazz.  One day when i was driving her car to work I saw it needed filling up and put almost a tank of Ultimate 97 in it.  I didn't tell her what I had done but later in the week she asked me if 'I had tuned the car' because even she had obviously noticed it was running better.  Needless to say she never used supermarket fuel again.  Now I would call that a proper blind trial because she had no idea I had put 97 in,  or even that I had filled the car really, and she noticed a difference, so that rules out the 'placebo' effect that someone may experience when they know they have done something and 'want' or expect it to have an effect.
Title: Re: MPG for those interested.
Post by: Kenneve on July 05, 2017, 09:49:37 PM
Hi Culzean
I should have said, that both cases, supermarket & main fuel company, we were talking 95RON fuel
I don't think I've ever used 97RON in my cars, certainly not in recent years.
Title: Re: MPG for those interested.
Post by: jazzway on July 06, 2017, 12:15:19 AM
About the Redex... it cleans more than the additives in petrol, but what happens with the dirt it losens? Does it solve and not float to another place? And how would you compare 95 octane petrol (with the 5-10 percent) ethanol plus Redex, to a higher octane petrol without ethanol and better additives (V-Power/BP Ultimate) without


If you have been using premium fuel your system will probably be pretty clean anyway, but purpose made system cleaners are not expensive.
I experience the difference — smoother drive (maybe between my ears) and a few percent better MPG compared to the Euro 95 petrol i used before. But with using a premium fuel without ethanol, an extra system cleaner might be overkill. And going back to a fuel with 5-10 percent ethanol will always give a decrease in MPG whatever cleaner i put in, i guess.

It sounds like a challenge between the most kilometers per litre (your MPG) for the lowest costs, but i really care about a clean system as we like to drive this Jazz for many more years. And ultimately that saves more on the long term. ;)


Anything that the cleaner dissolves is only stuff that is normally in fuel anyway and will just get injected and burned with fuel.
Thanks! I was wondering about that always, both with Redex and other brand cleaners.

Redex is not the only cleaner available Wynns, STP and others make similar product,  you only need to use it occasionally, add some to tank of fuel about once every one or two months - which means it is not expensive.
Again, with a premium fuel it might be overkill, or not?
Title: Re: MPG for those interested.
Post by: culzean on July 06, 2017, 08:30:25 AM
Hi Culzean
I should have said, that both cases, supermarket & main fuel company, we were talking 95RON fuel
I don't think I've ever used 97RON in my cars, certainly not in recent years.

My wife also uses 95 branded fuels now,  only when I fill her car up it gets the occasional tank of 97.  I have tried Tesco 99 a couple of times in Jazz and Civic and was happy enough with it but normally use Esso, BP or Shell, although I did notice my Civic seemed to like Total 95RON,  but no Total stations near where I live.
Title: Re: MPG for those interested.
Post by: Jocko on July 06, 2017, 12:42:01 PM
Bought a bottle of Redex Petrol Treatment (Asda, £3 for 250 ml), and popped half if it into my full tank (recommended amount). I'll see how I get along and keep the forum informed.
Title: Re: MPG for those interested.
Post by: culzean on July 10, 2017, 03:50:04 PM

https://www.todaytonightadelaide.com.au/stories/petrol-test (https://www.todaytonightadelaide.com.au/stories/petrol-test)

This Australian fuel test is interesting.
Title: Re: MPG for those interested.
Post by: Jocko on July 10, 2017, 04:17:07 PM
I would have been more convinced if they had tried all fuels in one car and one driver.
Title: Re: MPG for those interested.
Post by: mikebore on July 10, 2017, 04:17:26 PM
Five different vehicles involved  :D :D

They needed to at least repeat the test with the best fuel in the car which gave the worst result and vice versa.
Title: Re: MPG for those interested.
Post by: JohnAlways on July 10, 2017, 04:35:30 PM
You men 98 octane in the diesel and diesel in the 98 octane car. Sure the results would be startlingly different  :P
Title: Re: MPG for those interested.
Post by: mikebore on July 10, 2017, 04:38:41 PM
Ha Ha! They sure would!

I pretty much ignored the diesel being more interested in the difference between the petrol cars, so was suggesting switching those around.
Title: MPG for those interested.
Post by: jazzway on July 10, 2017, 04:52:22 PM

https://www.todaytonightadelaide.com.au/stories/petrol-test (https://www.todaytonightadelaide.com.au/stories/petrol-test)

This Australian fuel test is interesting.
"The problem with e10 isn't so much actually burning the alcohol in the engine. It is that the alcohol is hydroscopic; that it can actually absorb water from the atmosphere when it's in an open tank - particularly in the ground tank at the petrol station.

Water still can get into the fuel system and you may still have these problems of blocked filters and rough running. Even in a brand new car."


And that's why i fill with v-power without ethanol! :) Euro95 in the Netherlands is 5% and in Belgium it's e10 (10%) since January.
Title: Re: MPG for those interested.
Post by: Jocko on July 10, 2017, 05:26:16 PM
You men 98 octane in the diesel and diesel in the 98 octane car. Sure the results would be startlingly different  :P
Including the diesel in the test will be meaningful to some but I just ignored it!
Title: Re: MPG for those interested.
Post by: mikebore on July 10, 2017, 05:31:23 PM
I would have been more convinced if they had tried all fuels in one car and one driver.

I was actually surprised how close the 98 was to the Diesel. 55 to 59 "kays"

I don't know anything about the Hyundai i30 diesel but I doubt it was identical to the four petrol cars as the article says!
Title: Re: MPG for those interested.
Post by: Jocko on July 10, 2017, 05:39:24 PM
Found the Shell V-Power has 5% ethanol and, in Scotland, so has 98 RON Esso Synergy!
Title: Re: MPG for those interested.
Post by: Skyrider on July 10, 2017, 08:39:42 PM
That will be all the shale gas being imported into the Grangemouth refinery.  :-)
Title: Re: MPG for those interested.
Post by: jazzway on July 11, 2017, 11:37:21 AM
Found the Shell V-Power has 5% ethanol and, in Scotland, so has 98 RON Esso Synergy!
I thought that only in Belgium, the Netherlands and France V-Power does not contain ethanol. At the gas station in Belgium where i fill there's a big 'no ethanol in v-power' sign so okay for older cars. ;)
Title: Re: MPG for those interested.
Post by: Jocko on July 11, 2017, 12:44:04 PM
This is a response from Shell to an email request for information:
Thank you for your email. Please accept my personal apology for the delay of this response as we are currently receiving high volume of enquiries via email.

I can confirm that Shell V-Power unleaded contains up to 5% ethanol as stipulated by the European fuel specification EN228 and UK government legislation. In addition Shell FuelSave Regular Unleaded and Shell V-Power Nitro+ Unleaded also contain up to 5% ethanol. This is in order to respond to the European Union and UK government’s initiative to promote biofuels, whose aim is to reduce CO2 emissions and enhance energy supply security.

For the latest information on biofuel legislation in the UK, please consult the Department for Transport’s website http://www.dft.gov.uk/. (http://www.dft.gov.uk/.)

At Shell, we are passionate about fuel, and our dedicated fuel scientists work continuously in the lab to bring you the most advanced and effective fuels.

Once again, thank you for contacting Shell UK. We do hope you have found this information useful.
Title: Re: MPG for those interested.
Post by: Skyrider on July 11, 2017, 01:46:58 PM
This may be of interest.

https://www.whatcar.com/news/new-e10-fuel-will-cost-uk-motorists/ (https://www.whatcar.com/news/new-e10-fuel-will-cost-uk-motorists/)
Title: Re: MPG for those interested.
Post by: culzean on July 11, 2017, 02:48:22 PM
This may be of interest.

https://www.whatcar.com/news/new-e10-fuel-will-cost-uk-motorists/ (https://www.whatcar.com/news/new-e10-fuel-will-cost-uk-motorists/)

Typical muddled thinking,  ethanol often takes more energy to produce than it supplies, also why grow ethanol crops instead of food.  EU made a big mistake with bio diesel,  poor countries were destroying rain forest to plant Palm oil trees to supply Europe with 'green' bio oil,  I don't know if it is stupidity or vested interests at work here.
Title: MPG for those interested.
Post by: jazzway on July 11, 2017, 04:45:46 PM
This is a response from Shell to an email request for information:
...

The European fuel specification aside, in Belgium there is no ethanol in the Shell V-Power.
On the Shell website about the e10, of course in Dutch, but the last sentence (i made background yellow) says it: "If a vehicle is not suitable for Eurosuper 95 E10, it can use Shell V-Power, as there isn't processed bio-ethanol in it. "
(https://uploads.tapatalk-cdn.com/20170711/dd79614f1c928733a0ff002012c36c08.jpg)
Title: Re: MPG for those interested.
Post by: culzean on July 11, 2017, 06:17:01 PM
I have read that BP 97 ultimate does not contain ethanol but BP 95 does in UK..
Title: Re: MPG for those interested.
Post by: Jocko on July 11, 2017, 06:53:36 PM
Found this too.

BP - Ethanol is added at 5% to unleaded petrol at all sites across the UK, BP ultimate (super unleaded) does not have ethanol added except in the SW of England.
Esso_ Ethanol is added at 5% to unleaded petrol at most sites in the UK, Esso super unleaded does not contain ethanol except in the SW of England
Shell - Shell has repeatedly refused to answer the question, it is therefore an assumption only that all Shell petrol should be considered to contain 5% ethanol.
Texaco - Ethanol is added at 5% to unleaded petrol , Texaco super unleaded does not contain ethanol.
Total - ethanol is not added to any Total fuel including standard unleaded except in the NW and SE of England.
Title: Re: MPG for those interested.
Post by: andruec on July 16, 2017, 07:03:05 PM
Just for a laugh I put Tesco Premium into my Jazz this weekend and curiously the car is claiming round 60mg. It usually sits around 54mg. I have this week off work so that will complicate things
Title: Re: MPG for those interested.
Post by: Jocko on July 16, 2017, 08:35:51 PM
I too an going to try a premium fuel this next top up. I will be filling my tank, at Sainsbury's, on Friday (£2.50 off voucher), so I'll see what they've got and give it a try.
Title: Re: MPG for those interested.
Post by: d2d4j on July 16, 2017, 11:28:06 PM
Hi

I hope you don't mind, but to lighten the mood slightly, as I was waiting at a set of lights, I said a prayer to see if it helps my fuel consumption as behold, here's a pic of my mpg

(For those who do not realise, this is a little joke albeit the pic is correct, just minutes after filling up haha)

Many thanks

John(https://uploads.tapatalk-cdn.com/20170716/a7935e7db24334c3f8555824ac31ec38.jpg)
Title: Re: MPG for those interested.
Post by: TG on July 17, 2017, 12:00:03 AM
I bet it was plummeting as soon as the picture was taken, and where on earth is it only 10°?
--
TG
Title: Re: MPG for those interested.
Post by: d2d4j on July 17, 2017, 07:11:22 AM
Hi TG

Haha, plummeting is not the word for it.

I only took the picture to have a joke with my brother, and it started at over 100 mpg. By the time I had picked my mobile up, and took the picture, it had lost about 20mpg haha

Sorry, it's a few months old, so 10^ was considered warm

Many thanks

John
Title: Re: MPG for those interested.
Post by: andruec on July 18, 2017, 05:17:48 PM
Hmm. It's settled down to 58 mpg. That's higher than normal but could just be down to me being on vacation and not subject to Banbury rush hour. Still - it's interesting. It still seems a bit better than I'd expect which rather surprises me. I'd assumed that only performance engines could see a difference but maybe the Honda unit is so advanced that it can work more efficiently.
Title: Re: MPG for those interested.
Post by: peteo48 on July 18, 2017, 08:52:42 PM
This may be of interest.

https://www.whatcar.com/news/new-e10-fuel-will-cost-uk-motorists/ (https://www.whatcar.com/news/new-e10-fuel-will-cost-uk-motorists/)

Typical muddled thinking,  ethanol often takes more energy to produce than it supplies, also why grow ethanol crops instead of food.  EU made a big mistake with bio diesel,  poor countries were destroying rain forest to plant Palm oil trees to supply Europe with 'green' bio oil,  I don't know if it is stupidity or vested interests at work here.

I think, regardless of your take on climate change and air quality, some very odd decisions are made in an attempt to hit targets. I have never seen the sense of burning food to power transport and the decision to encourage diesel to hit CO2 targets must be one of the worst given the implications for air quality.
Title: Re: MPG for those interested.
Post by: culzean on July 18, 2017, 09:17:44 PM
Hmm. It's settled down to 58 mpg. That's higher than normal but could just be down to me being on vacation and not subject to Banbury rush hour. Still - it's interesting. It still seems a bit better than I'd expect which rather surprises me. I'd assumed that only performance engines could see a difference but maybe the Honda unit is so advanced that it can work more efficiently.

The knock sensor is there for a reason, it will retard the ignition until it senses knocking is down to a reasonable level that will not damage engine,  and by the same token can advance ignition when higher octane fuel is sensed and get a more complete burn by firing the spark earlier - even though high octane has got less energy in it than lower octane,  if the engine detects knocking and retards the ignition while using lower octane the extra energy is wasted as the charge is still burning as the piston is well down its stroke.
Title: Re: MPG for those interested.
Post by: culzean on July 18, 2017, 09:22:14 PM
I think, regardless of your take on climate change and air quality, some very odd decisions are made in an attempt to hit targets. I have never seen the sense of burning food to power transport and the decision to encourage diesel to hit CO2 targets must be one of the worst given the implications for air quality.

http://www.dailymail.co.uk/sciencetech/article-3661875/A-spotless-sun-Incredible-image-shows-solar-activity-quietest-100-years-say-trigger-mini-ice-age.html (http://www.dailymail.co.uk/sciencetech/article-3661875/A-spotless-sun-Incredible-image-shows-solar-activity-quietest-100-years-say-trigger-mini-ice-age.html)

Global warming,  they are having a laff - according to lack of sun activity we are heading for an ice age,  NASA say 'the effect of sun activity on global warmth is still a work in progress' - WTF even a 5 year old knows that when you turn a heater up you get hotter,  turn it down you get colder - think of the sun as the Earths heater.
Title: Re: MPG for those interested.
Post by: TG on July 18, 2017, 09:46:56 PM
WTF even a 5 year old knows that when you turn a heater up you get hotter,  turn it down you get colder - think of the sun as the Earths heater.
Was wearing my Montreal coat in New York one winter.......  the outside temp didn't matter - I was sweltering; the Earth keeps adding another coat.  Anyway a different set of scientists claim we are starting a new mass extinction event, might only be 10,000 years left.
--
TG
Title: Re: MPG for those interested.
Post by: Jocko on July 18, 2017, 09:59:18 PM
might only be 10,000 years left.
Wonder if they will have perfected the Autonomous Vehicle by then?
Title: Re: MPG for those interested.
Post by: andruec on July 18, 2017, 10:10:10 PM
I think, regardless of your take on climate change and air quality, some very odd decisions are made in an attempt to hit targets. I have never seen the sense of burning food to power transport and the decision to encourage diesel to hit CO2 targets must be one of the worst given the implications for air quality.

http://www.dailymail.co.uk/sciencetech/article-3661875/A-spotless-sun-Incredible-image-shows-solar-activity-quietest-100-years-say-trigger-mini-ice-age.html (http://www.dailymail.co.uk/sciencetech/article-3661875/A-spotless-sun-Incredible-image-shows-solar-activity-quietest-100-years-say-trigger-mini-ice-age.html)

Global warming,  they are having a laff - according to lack of sun activity we are heading for an ice age,  NASA say 'the effect of sun activity on global warmth is still a work in progress' - WTF even a 5 year old knows that when you turn a heater up you get hotter,  turn it down you get colder - think of the sun as the Earths heater.
Yes, but that's because a five year old doesn't understand complex systems.

The Earth does not react passively to solar heat. It reacts actively in ways that can cause cooling or heating. So it's a bit simplistic to say that a reduction in solar output is sure to result in cooling. Scientists think a solar minimum caused a mini ice age several hundreds years ago but we don't know if the biosphere will react the same way today.

There is evidence that something is causing a rise in global temperatures. There is even evidence that it is linked to industrialisation. So another solar minimum may just mean a slowing in global temperature rises. And when the sun returns to what we consider 'normal' heating is going to accelerate. So the best view on a mini ice age is that it might be a temporary respite followed by even more rapid heating.

I'm actually fairly neutral on the whole climate change thing - I just hate waste and think that polluting our environment is foolish.
Title: Re: MPG for those interested.
Post by: peteo48 on July 19, 2017, 10:21:51 AM
I think, regardless of your take on climate change and air quality, some very odd decisions are made in an attempt to hit targets. I have never seen the sense of burning food to power transport and the decision to encourage diesel to hit CO2 targets must be one of the worst given the implications for air quality.

http://www.dailymail.co.uk/sciencetech/article-3661875/A-spotless-sun-Incredible-image-shows-solar-activity-quietest-100-years-say-trigger-mini-ice-age.html (http://www.dailymail.co.uk/sciencetech/article-3661875/A-spotless-sun-Incredible-image-shows-solar-activity-quietest-100-years-say-trigger-mini-ice-age.html)

Global warming,  they are having a laff - according to lack of sun activity we are heading for an ice age,  NASA say 'the effect of sun activity on global warmth is still a work in progress' - WTF even a 5 year old knows that when you turn a heater up you get hotter,  turn it down you get colder - think of the sun as the Earths heater.
Yes, but that's because a five year old doesn't understand complex systems.

The Earth does not react passively to solar heat. It reacts actively in ways that can cause cooling or heating. So it's a bit simplistic to say that a reduction in solar output is sure to result in cooling. Scientists think a solar minimum caused a mini ice age several hundreds years ago but we don't know if the biosphere will react the same way today.

There is evidence that something is causing a rise in global temperatures. There is even evidence that it is linked to industrialisation. So another solar minimum may just mean a slowing in global temperature rises. And when the sun returns to what we consider 'normal' heating is going to accelerate. So the best view on a mini ice age is that it might be a temporary respite followed by even more rapid heating.

I'm actually fairly neutral on the whole climate change thing - I just hate waste and think that polluting our environment is foolish.

Pretty much my take Audrec. As a non scientist I am not really qualified to pronounce on the science one way or another but if Steven Hawking tells me something is going on I tend to pay attention to him.

That CO2 is a greenhouse gas is accepted by even climate change sceptics like Matt Ridley. My own view is that if we can move away from burning stuff to get power and if we can move away from dumping plastic in the oceans then we should do just that.
Title: Re: MPG for those interested.
Post by: Kenneve on August 22, 2017, 02:25:47 PM
Just had my first service today on my Mk3 EX Cvt.
Have covered 8465 miles over the past 12 months at, according to the readout, 52.4 Mpg.
This covers all types of motoring, except the daily commute to work, since i'm retired LOL

When i think back to the days when I used to drive various Landrovers & Rover V8 cars, with consumption figures approaching perhaps 1/3rd of the current figure, then i'm well pleased.
Title: Re: MPG for those interested.
Post by: VicW on August 22, 2017, 03:27:02 PM
In the early 80's I lived in Kuwait and bought an American car, a 7litre V8 Dodge Monaco. For the size of the engine the performance was poor and the fuel consumption was about 15mpg but at the equivalent of 8p a gallon who cared.
I decided to modify the engine and this involved going back in time to the previous years system.This did away with the emissions control unit and reverted to a basic ignition system which meant that I had to use higher grade fuel at 9p a gallon.Other mods included removing the twin catalytic converters,it was a twin exhaust exhaust system. There was no unleaded fuel available so the cats were clogged up. I removed two of the four silencers and changed the carburetor for a four choke one. The brakes were improved and stiffer dampers fitted.
I now had a car that had performance to suit a 7litre engine.
Most interesting of all was that the fuel consumption improved to 20mpg!

Vic.
Title: Re: MPG for those interested.
Post by: Jocko on August 22, 2017, 04:04:31 PM
I had a Triumph 2.5 PI which had iffy injectors. When I sold it I told the guy that I had to be honest and that I had had 16 mpg. He said that they could be thirsty. What I didn't tell him was 16 mpg was the best I had ever achieved, with 12 being nearer the average and once even 8 mpg!
I used to change the plugs on a daily basis.

(http://i.imgur.com/fnnop3e.jpg)
Title: Re: MPG for those interested.
Post by: Kenneve on August 22, 2017, 04:37:49 PM
I recall that as part of my job, I had to regularly travel from our Landrover plant in Solihull, down to our satellite plant in Cardiff, a round trip of roughly 220 miles. At the time the Rangerover had a 18 gallon fuel tank and if we pushed it hard, we could not get there and back, without a top up. Mind you if I remember correctly, fuel was around 4 gallons to £1, a might different to today!
Title: Re: MPG for those interested.
Post by: Jocko on August 22, 2017, 05:05:38 PM
When I started driving, in 1965, petrol at our local garages (no supermarkets then) was 4/4d a gallon (£0.047/litre).
We had 3 garages and a filling station selling petrol, in a small town of 5500 people. Now their nearest one is 6 miles away!
Title: Re: MPG for those interested.
Post by: culzean on August 22, 2017, 06:04:17 PM
Mind you if I remember correctly, fuel was around 4 gallons to £1, a might different to today!

How did average wages compare though ? We did an exercise with some of the older guys at work when I was younger,  basically the question was  'how many hours did you need to work to buy some basic commodities' and some surprising answers,  mostly stuff was cheaper than it used to be,  but there was just more stuff available for people to buy.
Title: Re: MPG for those interested.
Post by: Jocko on August 22, 2017, 06:21:00 PM
My 4/4d a gallon equates to £4.29 a gallon today, so cheaper but not a huge difference.
Title: Re: MPG for those interested.
Post by: mikebore on August 22, 2017, 06:53:30 PM
My 4/4d a gallon equates to £4.29 a gallon today, so cheaper but not a huge difference.

Don't understand...what am I missing ?
Title: Re: MPG for those interested.
Post by: Jocko on August 22, 2017, 08:08:14 PM
I have no idea how wages compared from then till now, but assuming wages increased at the same pace as prices, give or take, then petrol was slightly cheaper in 1965. Which may be down to lack of green taxes back then, purchase tax v VAT and the like.
Title: Re: MPG for those interested.
Post by: mikebore on August 22, 2017, 08:16:44 PM
What don't you understand?

Cancel that.Got it.
Title: Re: MPG for those interested.
Post by: Jocko on August 22, 2017, 08:25:36 PM
What don't you understand?

Cancel that.Got it.
I decided my original post wasn't very helpful, so I changed it!
Title: Re: MPG for those interested.
Post by: Downsizer on March 07, 2018, 05:03:13 PM
20,054 miles of mixed motoring completed in two years from new, and 1776.2 litres (usually ASDA 95) bought, giving 11.3 mpl or 51.3 mpg overall.  The averages shown by the car's instruments are 54.1 mpg and 34 mph.
Title: Re: MPG for those interested.
Post by: Jocko on March 07, 2018, 05:06:08 PM
Good figures. You must be pleased with that.
Title: Re: MPG for those interested.
Post by: peteo48 on March 19, 2018, 04:48:43 PM
Very early days but I was anxious to get an early indication of what mpg my new car doing so I filled up today having done only 145 miles since the last fill up. These 145 miles have been done in the very cold weather we have been having lately and mostly the urban cycle with the engine cold for much of the time.

In my 2 previous 1.4 manuals I would have expected a figure of around 35 mpg. Indeed my lowest ever - 33.8 - was "achieved" in very similar conditions.

Computer indicated 43.2 but the manual method (brim to brim) indicated 40.05.

So, very early days and a small sample mileage wise but I'm pleased. Looks like a 10% increase in mpg is on the cards. I've got the Fuelly.com BB code so this will show my average mpg as future fuel ups are added.
Title: Re: MPG for those interested.
Post by: culzean on March 19, 2018, 06:41:34 PM
On 400 mile trip around North Wales end of last week 1.8 Civic showed 48.5 mpg,  equating to about 45mpg  in very cold wet conditions (with Nokian WR-D3 winter tyres).  Even locally I get 45 mpg indicated,  I am driving carefully but not anally by any means,  just trying not to use brakes and short shifting when I think about it. 
Title: Re: MPG for those interested.
Post by: peteo48 on March 19, 2018, 08:09:08 PM
That's very good from a 1.8 Civic. I got over 40 very rarely although, being anal, I have kept records and there is a 47.7 in there and one or two mid 40s. Longer trips and you could get decent mpg. A more typical mpg for me was 35 ish.
Title: Re: MPG for those interested.
Post by: Downsizer on March 19, 2018, 10:36:57 PM
So, very early days and a small sample mileage wise but I'm pleased. Looks like a 10% increase in mpg is on the cards. I've got the Fuelly.com BB code so this will show my average mpg as future fuel ups are added.
7-10% improvement over a Mk 2 is a reasonable expectation based on my experience after 20,000 miles.
Title: Re: MPG for those interested.
Post by: peteo48 on March 20, 2018, 12:15:52 PM
Glad to hear it. I think the combination of changing to a Mk3 AND to a CVT should help my mpg significantly. Stop/Start - given that I do a lot of driving in traffic - should also contribute.
Title: Re: MPG for those interested.
Post by: Barcam on April 04, 2018, 02:08:46 PM
Have just completed 425 miles on my Honda Jazz Sport CVT. No problems of any kind and really pleased with the Car.

Done the calculations and the real mpg is 44.37 with the tank filled to just below the top of the petrol cap for a consistent calculation. The trip computer is optimistic by 2.48 mpg.

Did a short drive on the motorway for 15 miles and cruising at 70 mph (2200 rpm with the throttle backed off)  the trip showed 58 mpg.

Its as expected as most my trips are five miles from cold 50/50 split with country roads and town. Cold weather makes a big difference to the fuel consumption so I expect it will improve as the weather improves. I was getting pretty well identical mpg from my 2015 Fiesta Ecoboost 100 which was manual not an auto like the Jazz. Not only that the Jazz Sport would leave the Fiesta for dead any day. In my opinion the handling on the 2018 Jazz is as good as the Fiesta for normal driving, but of course I don't drive my car at 100% around corners.
Title: Re: MPG for those interested.
Post by: peteo48 on April 04, 2018, 05:14:01 PM
20,054 miles of mixed motoring completed in two years from new, and 1776.2 litres (usually ASDA 95) bought, giving 11.3 mpl or 51.3 mpg overall.  The averages shown by the car's instruments are 54.1 mpg and 34 mph.

Just revisited this thread and looked at this post again. This indicates that the car's computer is about 5-6% optimistic and that over a long period.

My very small sample over my first refill indicated a 5% discrepancy as well.

This is much better than the 10% error in the following cars: Golf 1.9TDI, Civic 1.8 (petrol), Jazz 1.4 x 2. These cars were all manual. Is there anything in the theory that a CVT or, indeed, any automatic will produce a more accurate computer reading? Fewer variables as computers are in charge?

Somebody with more technical knowledge than me needed!
Title: Re: MPG for those interested.
Post by: culzean on April 04, 2018, 05:38:43 PM
20,054 miles of mixed motoring completed in two years from new, and 1776.2 litres (usually ASDA 95) bought, giving 11.3 mpl or 51.3 mpg overall.  The averages shown by the car's instruments are 54.1 mpg and 34 mph.

Just revisited this thread and looked at this post again. This indicates that the car's computer is about 5-6% optimistic and that over a long period.

My very small sample over my first refill indicated a 5% discrepancy as well.

This is much better than the 10% error in the following cars: Golf 1.9TDI, Civic 1.8 (petrol), Jazz 1.4 x 2. These cars were all manual. Is there anything in the theory that a CVT or, indeed, any automatic will produce a more accurate computer reading? Fewer variables as computers are in charge?

Somebody with more technical knowledge than me needed!

The smoother your driving the more accurate the MPG display will be on most cars.  The system takes a snapshot about every 10 seconds (you will see MPG display update at the same time) - If you zero a  trip every time you fill up you will notice the MPG display is most sensitive for the first 50 miles or so,  after that it is averaging the 'instantaneous' MPG over more miles on the trip and any change in driving makes less difference to MPG readout.  ECU uses fuel injector 'open' times (which are variable depending on engine temp, accelerator pedal position etc)  to work out the rate at which fuel is been squirted into engine at time of snapshot and how far car has travelled since last snapshot to come up with an MPG figure (averaged out over miles presently on trip mileage readout).  Probably because the ECU takes a snapshot every 10 seconds or so it can be more accurate if not much changes during the 10 seconds since last snapshot (smooth driving) if your driving is erratic things change quickly and a lot can happen in 10 seconds between shots (rapid acceleration and deceleration) which gives a less accurate reading.
Title: Re: MPG for those interested.
Post by: Downsizer on April 04, 2018, 10:07:04 PM
20,054 miles of mixed motoring completed in two years from new, and 1776.2 litres (usually ASDA 95) bought, giving 11.3 mpl or 51.3 mpg overall.  The averages shown by the car's instruments are 54.1 mpg and 34 mph.

Just revisited this thread and looked at this post again. This indicates that the car's computer is about 5-6% optimistic and that over a long period.

My very small sample over my first refill indicated a 5% discrepancy as well.

This is much better than the 10% error in the following cars: Golf 1.9TDI, Civic 1.8 (petrol), Jazz 1.4 x 2. These cars were all manual. Is there anything in the theory that a CVT or, indeed, any automatic will produce a more accurate computer reading? Fewer variables as computers are in charge?

Somebody with more technical knowledge than me needed!
The combination of CVT and cruise control certainly cuts out some unnecessary right foot twitching.
Title: Re: MPG for those interested.
Post by: t5nel on May 02, 2018, 09:19:28 PM
First brim to brim (390 miles) in a brand new 1.3 manual SE

Honda says 52.8 the pump (and fuelly) says 50.8mpg

Very happy with that.  Has mostly been commuting schools runs and kids taxi duty

Tim
Title: Re: MPG for those interested.
Post by: Jocko on May 02, 2018, 09:39:39 PM
Excellent. You cannot complain about those figures.
Title: Re: MPG for those interested.
Post by: Skyrider on May 10, 2018, 12:26:13 PM
First tank was 43mpg driven normally but not exceeding 4,000 rpm. Reasonable for a tight 1.5 engine.
Title: Re: MPG for those interested.
Post by: peteo48 on May 10, 2018, 12:31:13 PM
I think those figures are pretty good. Demonstrates to me that, despite the difference in the NEDC figures between the 1.3 and the 1.5, in the real world they will be much closer. The 1.5 will be less stressed.

I either read this in Which or Honest John but larger engine cars get closer to the "official" figures than some of these smaller engine cars.
Title: Re: MPG for those interested.
Post by: Skyrider on May 10, 2018, 01:17:34 PM
I have just read Barcam's post above, I note that our first tank fuel consumptions are similar. We obviously both drive in the real world. :-)
Title: Re: MPG for those interested.
Post by: Barcam on May 10, 2018, 02:06:10 PM
I have just read Barcam's post above, I note that our first tank fuel consumptions are similar. We obviously both drive in the real world. :-)

Getting to the refill stage on my last tank of petrol so it will be interesting to see what effect the warm weather has on the mpg. Most of the time I don't belt the car what is the point in nose to tail traffic. I mainly use the power of the 1.5 engine for pulling away at road junctions and roundabouts.
Title: Re: MPG for those interested.
Post by: peteo48 on May 17, 2018, 03:33:44 PM
My third tank came out at 42.2 mpg leaving an average of 41.6 over 585 miles. 80% of the driving has been town stuff and the average speed of 17 mph perhaps tells you all you need to know about where I do most of my driving.

Not great but not bad either. Unfortunately I haven't yet had the chance to do any significant distance driving.
Title: Re: MPG for those interested.
Post by: peteo48 on June 15, 2018, 04:03:11 PM
Just had a refill which gave me just over 50 mpg. 65% city driving so I'm well pleased. The weather helps but, looking back at my Mk2s, I only got over 50 mpg if I was at 10% city driving.
Title: Re: MPG for those interested.
Post by: mikebore on June 15, 2018, 04:53:04 PM
Just had a refill which gave me just over 50 mpg. 65% city driving so I'm well pleased. The weather helps but, looking back at my Mk2s, I only got over 50 mpg if I was at 10% city driving.

FWIW:

My Mk2 CVT averaged 43.3 mpg over 25,761 miles of very mixed motoring in a 22 month period.

My Mk3 CVT has averaged 46.1 mpg over 28,383 miles of similar mixed motoring in a 24 month period.

The above two numbers are very comparable as our usage has not changed over the last four years.


I have not tried to record city vs non-city driving...are your percentages subjective or are you recording it somehow?

Title: Re: MPG for those interested.
Post by: peteo48 on June 15, 2018, 10:30:10 PM
I read a thread on Fuelly about how Americans would record city versus highway. City was an average of 22 mph and highway an average of 49 mph.

In the UK I use the difference between urban (an average speed of 12 mph) and extra urban (an average speed of 39mph). You deduct 12 mph from whatever your average speed on the computer is, multiply that by 100, divide by 27 and that gives you your highway (or extra urban) percentage.

Oddly, in both cases, the difference between the 2 sets of figures is 27.

So, in my case, I'm saying that 65% of my driving is urban - ie very short journeys with lots of gear changes and the engine below operating temperature.
Title: Re: MPG for those interested.
Post by: Skyrider on July 10, 2018, 10:10:00 AM
On Sunday morning I drove from Haydock to High Wycombe in light traffic,180ish miles, cruise control, 70 mph all the way. The cars info screen was showing an average of 60 mpg which I expected to be 4 mpg optimistic judging from my 1.3 Jazz. The full to full calculation was 58 mpg. I did not believe the calculation and got Mrs Sky to check it, we agreed (a novelty) that the calculation was correct. I am amazed, a bit better than the 37 mpg I have achieved in different conditions, or when "making progress".
Title: Re: MPG for those interested.
Post by: culzean on July 10, 2018, 11:30:48 AM
On Sunday morning I drove from Haycock to High Wycombe in light traffic,180ish miles, cruise control, 70 mph all the way. The cars info screen was showing an average of 60 mpg which I expected to be 4 mpg optimistic judging from my 1.3 Jazz. The full to full calculation was 58 mpg. I did not believe the calculation and got Mrs Sky to check it, we agreed (a novelty) that the calculation was correct. I am amazed, a bit better than the 37 mpg I have achieved in different conditions, or when "making progress".

The hot weather and constant speed all contribute to good MPG.  and the smoother the drive the more accurate the onboard MPG display.
Title: Re: MPG for those interested.
Post by: Barcam on July 10, 2018, 11:54:44 AM
On Sunday morning I drove from Haycock to High Wycombe in light traffic,180ish miles, cruise control, 70 mph all the way. The cars info screen was showing an average of 60 mpg which I expected to be 4 mpg optimistic judging from my 1.3 Jazz. The full to full calculation was 58 mpg. I did not believe the calculation and got Mrs Sky to check it, we agreed (a novelty) that the calculation was correct. I am amazed, a bit better than the 37 mpg I have achieved in different conditions, or when "making progress".

I was on the motorway the other day, cruise control at 70 showing 58mpg, great I thought then I hit a big traffic jam for twenty minutes, mpg dropped to 54. Heavy stop/start traffic makes a big difference to the fuel consumption. I must admit I put my foot down on the way home, that makes a noticeable difference.
Title: Re: MPG for those interested.
Post by: Downsizer on July 10, 2018, 04:14:48 PM
On Sunday morning I drove from Haycock to High Wycombe in light traffic,180ish miles, cruise control, 70 mph all the way. The cars info screen was showing an average of 60 mpg which I expected to be 4 mpg optimistic judging from my 1.3 Jazz. The full to full calculation was 58 mpg. I did not believe the calculation and got Mrs Sky to check it, we agreed (a novelty) that the calculation was correct. I am amazed, a bit better than the 37 mpg I have achieved in different conditions, or when "making progress".
Cruise control at 70 mph would be a true 66 mph on mine, based on Satnav reading.
Title: Re: MPG for those interested.
Post by: Skyrider on July 10, 2018, 06:46:42 PM
On Sunday morning I drove from Haycock to High Wycombe in light traffic,180ish miles, cruise control, 70 mph all the way. The cars info screen was showing an average of 60 mpg which I expected to be 4 mpg optimistic judging from my 1.3 Jazz. The full to full calculation was 58 mpg. I did not believe the calculation and got Mrs Sky to check it, we agreed (a novelty) that the calculation was correct. I am amazed, a bit better than the 37 mpg I have achieved in different conditions, or when "making progress".
Cruise control at 70 mph would be a true 66 mph on mine, based on Satnav reading.

Excellent, no speeding tickets.
Title: Re: MPG for those interested.
Post by: Skyrider on July 15, 2018, 01:26:54 PM
I have completed my trip to the south, total 978 miles, no motorway holdups, 70 mph on cruise control apart from a few road works at 50 mph, a couple of days light London traffic included. Fuel consumption calculated full to full for the 978 miles, 48 mpg.
Title: Re: MPG for those interested.
Post by: Jocko on July 15, 2018, 02:36:36 PM
You will be pleased with that.
Title: Re: MPG for those interested.
Post by: Skyrider on July 15, 2018, 03:49:09 PM
You will be pleased with that.

Yes, no complaints, just a shame it is not always that good. The hooligan mpg is not so clever. :-)
Title: Re: MPG for those interested.
Post by: peteo48 on July 23, 2018, 03:17:25 PM
Last 2 fills, including one today, have been just over 50 mpg and just under 50 mpg. My average now nudging 45 and that's over a 1000 miles with the extended winter, in part, offsetting the glorious summer.

I think it's going to pan out with the Mk3 CVT being, give or take, about 10% better than the Mk2 manual. Reasonably content with that.

Still a long way behind Jocko :)
Title: Re: MPG for those interested.
Post by: Downsizer on July 23, 2018, 04:42:45 PM
I think it's going to pan out with the Mk3 CVT being, give or take, about 10% better than the Mk2 manual. Reasonably content with that.
That mirrors my experience over 20,000 miles.
Title: Re: MPG for those interested.
Post by: andruec on July 24, 2018, 04:22:14 PM
Min peaked this year at 56mpg (mainly rural, some urban rush hour) back in May. But since the glorious summer weather really began to bite the figure has dropped. Last fill was 53mpg which is presumably the cost of the air conditioning. It always amuses when me I set off and the climate control starts winding up the fan. Takes it about five minutes before it starts to let it drop back from full speed.

I still don't think the Honda cabin air flow is as good as Nissan's. I'm sure my last Nissan (an Almera) rarely took more than five minutes to get the cabin temperature down whereas the Jazz can take ten minutes before it stops feeling hot and sometimes the fan is still going strong twenty minutes later as I arrive home.
Title: Re: MPG for those interested.
Post by: Skyrider on July 24, 2018, 06:06:32 PM
Min peaked this year at 56mpg (mainly rural, some urban rush hour) back in May. But since the glorious summer weather really began to bite the figure has dropped. Last fill was 53mpg which is presumably the cost of the air conditioning. It always amuses when me I set off and the climate control starts winding up the fan. Takes it about five minutes before it starts to let it drop back from full speed.

I still don't think the Honda cabin air flow is as good as Nissan's. I'm sure my last Nissan (an Almera) rarely took more than five minutes to get the cabin temperature down whereas the Jazz can take ten minutes before it stops feeling hot and sometimes the fan is still going strong twenty minutes later as I arrive home.

Try Australian routine, Aircon on full cold, fan on full speed, recirc on. When the car cools down recirc off and set the aircon and fan to a comfortable level. The Aussies turn the Aircon off if it is a short journey to allow the car to warm a bit so no thermal shock when they get out. If you have climate control, tough, you have Honda's set up, like it or not. I never turn my Aircon off.
Title: Re: MPG for those interested.
Post by: andruec on July 24, 2018, 06:41:43 PM
Yeah the climate control automatically activates recirc mode. I leave mine set at 19 degrees, auto most of the time. Over winter I select 'screen and feet' for the vents though because the CC isn't very clever about reducing condensation. It starts off blowing at the windscreen but goes back to cabin within a minute. Unsurprisingly the screen starts misting up almost immediately after that.
Title: Re: MPG for those interested.
Post by: Robbie MkII on August 20, 2018, 08:02:40 PM
Update:  I have today checked mpg after an 850-mile trip to Scotland (and a week's worth of buzzing about) AND a weekend to London (that's around another 400 miles) with a little local driving in between.

Around half will have been almost fully-laden at legal ( well, 'ish' ) motorway speeds with the rest a mix of 60/70 'A' roads, rural and congestion (A1 roadworks, M25 etc.).
I'm no Jenson Button, using the power available as and when needed rather than for sheer hooliganism.
Well, mostly.  ;)
Remember too that this is a manual 1.5 - and it's a babe yet with only 2,400 on the clock so it hasn't even fully loosened up yet.

Have I built enough suspense?
Okay, brim-to-brim over 1400 miles = 46.15 mpg
Without "trying", so I'm mightily impressed.



Title: Re: MPG for those interested.
Post by: Skyrider on August 20, 2018, 08:20:57 PM
Definitely a hooligan, I got 48 on a similar trip when my 1.5 was nearly new. ;D

See my post back a page. Maybe you did more running around than me.
Title: Re: MPG for those interested.
Post by: Robbie MkII on August 21, 2018, 09:48:24 AM
Yeah yeah yeah.  ::)
It  was all the short stop-start trips and stationary in traffic wot dun it otherwise it would have been 50 EASY!  ;D

Seriously though, in a similar trip in our Seat Mii (60bhp 3-cyl) but with less weight on board we only managed just under 50mpg (car average 50.8) so I'm impressed.

Like many who buy the Sport I suppose, we don't buy it for the economy and if I hadn't had my interest piqued by this thread I might not even have checked.
But I reckon in normal use (25-odd miles per day on mostly winding country roads with plenty gear changes on the many tight bends) I will see nigh-on 50mpg, which is within a gnats of what my 02 Jazz SE Sport used to do.
I will keep this thread updated of course but to me that's really very good for this. For example I couldn't see the competition (what there is of it, not mentioning names) getting close to that.

The real bonus is the look on would-be hooligan drivers faces as you leave them standing.
 8)

Title: Re: MPG for those interested.
Post by: Skyrider on August 21, 2018, 10:00:35 AM
Yeah yeah yeah.  ::)
The real bonus is the look on would-be hooligan drivers faces as you leave them standing.
 8)

I have noticed that too, you can almost hear them thinking "A Jazz shouldn't do that!" or words to that effect!  :o
Title: Re: MPG for those interested.
Post by: Sidot on August 22, 2018, 04:33:57 PM
Took car back for trade in for Jazz SE CVT.
Didn't want to change but had to get an automatic owing to worsening arthritis in left leg.
Anyway.....drew a line under my petrol book for this car and the details are......
16754 miles covered
401.78 gallons used
Resultant mpg = 41.69

Mileage is mainly urban, with three driving holidays and some long distance runs.

Works out about four mpg better than previous Mk2 1.2 engine.

Interestingly petrol cost when had the car £1.03 per gallon price now £1.29.
An increase of 21% !!

Is there no end to spiralling fuel prices ?

Hoping for similar or better mpg on CVT.
Title: Re: MPG for those interested.
Post by: JazzyJJ on August 30, 2018, 06:34:39 PM
From Honest Johns weekly email newsletter (received today 30 Aug 2018)

"The Honda Jazz 1.3-litre petrol has proven to be a Real MPG winner in August, averaging at 97 per cent of its official economy. That means Real MPG drivers get at least 53mpg on the road - just a couple of points short of the advertised 54-55mpg..."
Title: Re: MPG for those interested.
Post by: Skyrider on August 30, 2018, 08:07:12 PM
From Honest Johns weekly email newsletter (received today 30 Aug 2018)

"The Honda Jazz 1.3-litre petrol has proven to be a Real MPG winner in August, averaging at 97 per cent of its official economy. That means Real MPG drivers get at least 53mpg on the road - just a couple of points short of the advertised 54-55mpg..."

What planet is he on? OK I have had 60mpg on a long quiet motorway journey, but in real life day to day use, no way.
Title: Re: MPG for those interested.
Post by: peteo48 on August 30, 2018, 09:27:10 PM
I remember looking at the Honest John Website where they collect data for real life mpg. Last time I looked they asked you to record what the onboard computer shows which is, usually, around 5 mpg optimistic so the figures on that site are almost worthless.

Just filled up incidentally. 42.3 mpg only mostly urban cycle type driving. Overall I'm showing 44.4. I'm quite happy with that given that my average speed is about 18 mph showing that nearly all my motoring is in heavy traffic.
Title: Re: MPG for those interested.
Post by: Skyrider on August 30, 2018, 09:38:44 PM
Mine has settled in the low 40s mpg for daily running about, as with most cars it is better on a long run.
Title: Re: MPG for those interested.
Post by: Jocko on August 30, 2018, 09:47:50 PM
My average speed with my Mk 1 is 30 mph, 30 mph, 27 mph and 30 mph (recorded over the last 4 tankfuls).
Title: Re: MPG for those interested.
Post by: ColinB on August 31, 2018, 07:32:07 AM
I remember looking at the Honest John Website where they collect data for real life mpg. Last time I looked they asked you to record what the onboard computer shows which is, usually, around 5 mpg optimistic so the figures on that site are almost worthless.
And of course the folks who bother to report will be those who are pleased with their MPG so the figures will have a natural optimistic bias.
Title: Re: MPG for those interested.
Post by: Jocko on August 31, 2018, 08:51:33 AM
For my model Jazz I actually get 106% of the official mpg and 117% of Honest John's Real MPG. Honest John gives Real MPG as 91% of official figure. 46.5 mpg as against 51.4 mpg,  and my two year average is 54.3 mpg.
These figures are for the 2001 - 2008 1.2i.
Title: Re: MPG for those interested.
Post by: Jocko on August 31, 2018, 09:24:01 AM
Last time I looked they asked you to record what the onboard computer shows
I had a good search of the Honest John site and can find no mention of recording what the computer says. It just asks for your real mpg. Mind you, the majority of motorists these days just go by their onboard computer and no longer calculate what they are actually getting.
Title: Re: MPG for those interested.
Post by: Downsizer on August 31, 2018, 09:31:14 AM
The key variables are where and how the car is driven.  I have no problem averaging real world 52 mpg, but the average speed is 34 mph and in largely rural and flat East Anglia.
Title: Re: MPG for those interested.
Post by: peteo48 on August 31, 2018, 10:11:54 AM
Last time I looked they asked you to record what the onboard computer shows
I had a good search of the Honest John site and can find no mention of recording what the computer says. It just asks for your real mpg. Mind you, the majority of motorists these days just go by their onboard computer and no longer calculate what they are actually getting.

I wonder if he's changed it then. I confess it was a few years ago when I looked and I remember thinking at the time that this would give an inaccurate picture.

On the onboard computer, I guess it's OK if you aren't too fussed about accuracy and it will show up any sudden changes. I find it about 4 mpg optimistic.

I've got a pal who is a money saving fanatic. Extra jumpers rather than turn up the central heating, keen collector of money off vouchers, buys all his clothes from Asda but he doesn't bother with mpg just putting £20 in when the light comes on.
Title: Re: MPG for those interested.
Post by: Jocko on August 31, 2018, 11:22:50 AM
The key variables are where and how the car is driven.  I have no problem averaging real world 52 mpg, but the average speed is 34 mpg and in largely rural and flat East Anglia.
Similar figures and circumstances as myself, though it is not all that flat around here!
Title: Re: MPG for those interested.
Post by: andruec on August 31, 2018, 11:52:55 AM
I achieved a new personal record. Went up to Yorkshire for a few days. On the way up the M1 I stayed in lane one with the CC on at 60mph until I got to the 50mph roadworks. Just after the roadworks ended my car was showing 71.2mpg :)

Having driven 360 miles I still have a third of a tank left according to the fuel gauge. Sadly that will fall rapidly once I get back to commuting next week :(
Title: Re: MPG for those interested.
Post by: peteo48 on August 31, 2018, 12:18:23 PM
Sounds a bit like another pal of mine who, a few years ago, in his Mk1 Jazz, did an economy run on his way back to the North West from East Anglia. He stayed at 60 where possible and was helped considerably by a few long stretches of 50 mph. I forget the exact figure but it was in the high 60s on the computer so probably 65 ish.
Title: Re: MPG for those interested.
Post by: Jocko on August 31, 2018, 01:14:31 PM
My best calculated mpg for a tankful was 62. That did include a 75 mile, Sunday afternoon run out for ice cream! Obviously it was during the summer!!
I have had a calculated 66 mpg at a top up but it was a short fill up, after only 100 miles, so that doesn't count.
Title: Re: MPG for those interested.
Post by: andruec on August 31, 2018, 06:32:03 PM
Well we'll find out the actual MPG either tomorrow or Sunday. I have two more local golf courses to drive to and hopefully I can do that and fill up ready for the week ahead.
Title: Re: MPG for those interested.
Post by: VicW on August 31, 2018, 06:54:32 PM
Something for you mpg enthusiasts:-

https://www.autoexpress.co.uk/car-news/104466/what-is-hypermiling-and-how-do-you-do-it?_mout=1&utm_campaign=autoexpress_newsletter&utm_medium=email&utm_source=newsletter

Vic.
Title: Re: MPG for those interested.
Post by: andruec on August 31, 2018, 07:30:23 PM
The biggest gain for most people would be not using the brakes except in emergencies and when coming to a halt. Learn to plan ahead and anticipate traffic flow. Lift off early. Even though I drive an automatic with a CVT I can still drive hundreds of miles without ever having to touch the brake pedal.
Title: Re: MPG for those interested.
Post by: Skyrider on August 31, 2018, 07:37:49 PM
The biggest gain for most people would be not using the brakes except in emergencies and when coming to a halt. Learn to plan ahead and anticipate traffic flow. Lift off early. Even though I drive an automatic with a CVT I can still drive hundreds of miles without ever having to touch the brake pedal.

Do let us know when your brake calipers seize up from lack of use, it will be the rear ones first.
Title: Re: MPG for those interested.
Post by: Jocko on August 31, 2018, 08:00:56 PM
Do let us know when your brake calipers seize up from lack of use, it will be the rear ones first.
I seldom use the brakes and drove more than 100,000 miles with my Cavalier and never experienced brake issues. Don't know about the Jazz though. Only done 20,000 miles with that so far.
Title: Re: MPG for those interested.
Post by: Skyrider on August 31, 2018, 08:14:23 PM
Do let us know when your brake calipers seize up from lack of use, it will be the rear ones first.
I seldom use the brakes and drove more than 100,000 miles with my Cavalier and never experienced brake issues. Don't know about the Jazz though. Only done 20,000 miles with that so far.

I can only assume that your brakes were well maintained, unlike the Jazz service schedule requirements.
Title: Re: MPG for those interested.
Post by: andruec on August 31, 2018, 08:37:36 PM
The biggest gain for most people would be not using the brakes except in emergencies and when coming to a halt. Learn to plan ahead and anticipate traffic flow. Lift off early. Even though I drive an automatic with a CVT I can still drive hundreds of miles without ever having to touch the brake pedal.

Do let us know when your brake calipers seize up from lack of use, it will be the rear ones first.
Callipers are unlikely to be a problem however corroded discs could be. They will still last longer than those of a typical driver but it might smart a bit to have to replace discs because they have too much surface pitting and aren't worth skimming down.
Title: Re: MPG for those interested.
Post by: ColinS on August 31, 2018, 08:38:25 PM
In the last 30 months I have driven 34,000 miles without trying to drive economically and achieved 50.36 mpg (real, not computer).  If I changed my driving techniques as suggested by some, I may achieve savings of optimistically 10% and that would save me £12 per month.

In the overall scheme of things I think I will just continue to enjoy my driving.
Title: Re: MPG for those interested.
Post by: Skyrider on August 31, 2018, 08:47:57 PM
In the last 30 months I have driven 34,000 miles without trying to drive economically and achieved 50.36 mpg (real, not computer).  If I changed my driving techniques as suggested by some, I may achieve savings of optimistically 10% and that would save me £12 per month.

In the overall scheme of things I think I will just continue to enjoy my driving.

Exactly, life's too short for extreme economy driving, if you can't afford the fuel use a bus. Free for me but I rarely use them. Just drive it, it is about as economical a petrol car as you can get.
Title: Re: MPG for those interested.
Post by: peteo48 on August 31, 2018, 09:06:34 PM
In the last 30 months I have driven 34,000 miles without trying to drive economically and achieved 50.36 mpg (real, not computer).  If I changed my driving techniques as suggested by some, I may achieve savings of optimistically 10% and that would save me £12 per month.

In the overall scheme of things I think I will just continue to enjoy my driving.

Exactly, life's too short for extreme economy driving, if you can't afford the fuel use a bus. Free for me but I rarely use them. Just drive it, it is about as economical a petrol car as you can get.

I think that is the right attitude (within reason). I am not completely sure where my obsession with keeping records of mpg comes from. The correct balance is to drive thoughtfully but not be afraid to call on extra power when needed.
Title: Re: MPG for those interested.
Post by: Jocko on August 31, 2018, 09:32:31 PM
I have been driving for economy for the last year, not to save petrol but just as a game, to see how good mpg I can get. I accelerate briskly and make excellent progress but still achieve excellent mpg. I have always driven with minimum use of the brakes. Always found it a smooth, safe way to drive. I love driving, and get great enjoyment from it. I tend to drive at no more than 55 - 60 mph, but take corners at speed that many motorists would never dream of.
I have had performance driving training, done a little rally driving, ridden bikes and as I have posted before, even had a go in single seaters. I have driven buses and lorries over the years. I just love driving.
If I wanted to save money I would use my free bus pass, but I neither need to or want to.
Title: Re: MPG for those interested.
Post by: peteo48 on August 31, 2018, 09:38:00 PM
Good answer Jocko!
Title: Re: MPG for those interested.
Post by: andruec on September 01, 2018, 07:12:15 AM
I have been driving for economy for the last year, not to save petrol but just as a game, to see how good mpg I can get. I accelerate briskly and make excellent progress but still achieve excellent mpg. I have always driven with minimum use of the brakes. Always found it a smooth, safe way to drive. I love driving, and get great enjoyment from it. I tend to drive at no more than 55 - 60 mph, but take corners at speed that many motorists would never dream of.
You sound a lot like me. I've always driven with economy in mind (I do most things in life economically, possibly because of my long computer programming career). I think those dismissing efficient driving are perhaps unaware that it can make it more interesting and fun. You have to be so much more aware of what's going on around and coming up. More engaged in what can otherwise be seen as a boring experience. It probably make me a safer driver as well. I don't track mpg and but I do calculate the pump to pump figure after each fill.

And yes, I take corners quickly. Always mindful of visibility and road surface of course but I know what my car can do.
Title: Re: MPG for those interested.
Post by: culzean on September 01, 2018, 08:34:38 AM
I have been driving for economy for the last year, not to save petrol but just as a game, to see how good mpg I can get. I accelerate briskly and make excellent progress but still achieve excellent mpg. I have always driven with minimum use of the brakes. Always found it a smooth, safe way to drive. I love driving, and get great enjoyment from it. I tend to drive at no more than 55 - 60 mph, but take corners at speed that many motorists would never dream of.
You sound a lot like me. I've always driven with economy in mind (I do most things in life economically, possibly because of my long computer programming career). I think those dismissing efficient driving are perhaps unaware that it can make it more interesting and fun. You have to be so much more aware of what's going on around and coming up. More engaged in what can otherwise be seen as a boring experience. It probably make me a safer driver as well. I don't track mpg and but I do calculate the pump to pump figure after each fill.

And yes, I take corners quickly. Always mindful of visibility and road surface of course but I know what my car can do.

I am not by any means OCD when it comes to mpg but I do like to see how driving style etc. affects fuel used.  I drive pretty smoothly anyway and I know from when I used to track pump to pump and miles covered that the onboard display is within 5% (optimistic) - I like to carry momentum and not waste energy in the brakes.  As you say,  it makes you think ahead and observe traffic better, especially at islands where I like to slot in without stopping if I can (without causing others to brake).  It does make driving more interesting,  too many people get in a vehicle and either switch their brain off or get distracted by gadgets.
Title: Re: MPG for those interested.
Post by: peteo48 on September 01, 2018, 10:01:03 AM
Interesting points of view. I don't like waste generally so I have never been a foot to the floor merchant and, in recent years, I've become more conscious of the benefits of driving smoothly. To use the modern phrase - I try to practice "mindful" driving and I guess that's what the posters above are talking about.

I will admit to using "S" mode and the paddles from time to time but I see that as entirely justified when I need a burst of acceleration.
Title: Re: MPG for those interested.
Post by: Skyrider on September 01, 2018, 11:57:00 AM
I will admit to using "S" mode and the paddles from time to time but I see that as entirely justified when I need a burst of acceleration.

With the 1.3 engine acceleration needs all the help it can get! An excellent engine spoiled by its setup. It could have been so much better.
Title: Re: MPG for those interested.
Post by: trebor1652 on September 01, 2018, 12:01:37 PM
Just done a journey down the dreaded M6/m5/m42/m40. 70mph when possible and the onboard computer finished at 60 mpg.
Pleased with that normal town driving about 44mpg. Mk3 CVT.

Sent from my moto g(6) using Tapatalk

Title: Re: MPG for those interested.
Post by: peteo48 on September 01, 2018, 02:21:17 PM
I will admit to using "S" mode and the paddles from time to time but I see that as entirely justified when I need a burst of acceleration.

With the 1.3 engine acceleration needs all the help it can get! An excellent engine spoiled by its setup. It could have been so much better.

Indeed. That's why I don't mind assisting it from time to time!
Title: Re: MPG for those interested.
Post by: Jocko on September 01, 2018, 02:37:05 PM
Just completed my weekly round trip to Danderhall, south of Edinburgh. An 80 mile trip, 50 miles of which were busy dual carriageway/motorway (not that there is a lot of difference up here in Scotland), with the rest town or country roads. According to my ScanGauge (more accurate than onboard computer but not as accurate as calculated figure) I achieved 60 mpg at an average speed of 40 mph.
Title: Re: MPG for those interested.
Post by: culzean on September 01, 2018, 03:55:30 PM
Just done a journey down the dreaded M6/m5/m42/m40. 70mph when possible and the onboard computer finished at 60 mpg.
Pleased with that normal town driving about 44mpg. Mk3 CVT.

Sent from my moto g(6) using Tapatalk

Used to do M54 / M6 / M5 / M42 / M40 to Thame at least once a month and often several times a month, would start at 6am and not get back home till 10pm, our companies head office was just outside Thame and monthly site managers meetings and all sorts of HR and Health and Safety courses held there. I was the most far flung of the site managers and absolutely hated those journeys  :'(

Retired now - loving it  :D
Title: Re: MPG for those interested.
Post by: andruec on September 01, 2018, 05:41:31 PM
Well the figures are in: 55.1 mpg. Not as good as I'd initially hoped but then I realised that apart from 280 miles of sedate motorway driving it includes 80 miles of up hill and down dale (almost literally) in and around the Holmfirth area. Beautiful, yes, but a not a pleasant place to drive a car around. Narrow twisty roads and most of them are at a 45 degree angle :(

Mad junctions - The left-most road in the distance (https://goo.gl/maps/SsRdp1iXTD82) leads up to the apartment I rented.

Getting to one of the golf courses I visited required me to make that 180 degree left-hand turn (https://goo.gl/maps/7dYVjer6ymp). I barely made it even with the help of a driver who kindly waited for me so that I could use the entire width of the road.
Title: Re: MPG for those interested.
Post by: Brian_I on September 01, 2018, 09:46:15 PM
44mpg (calculated brim to brim) over the last 211 miles, mainly short journeys, although a steady cruise to Glasgow and Back along the M8 (50mpg according to trip computer for that trip). 

Trip computer showed 48.1mpg average for the 211 miles.  So quite a difference between trip computer & average mpg as calculate from brim to brim fills. (2013 MK2 Jazz 1.4 EX Plus).
Title: Re: MPG for those interested.
Post by: peteo48 on September 01, 2018, 10:41:13 PM
44mpg (calculated brim to brim) over the last 211 miles, mainly short journeys, although a steady cruise to Glasgow and Back along the M8 (50mpg according to trip computer for that trip). 

Trip computer showed 48.1mpg average for the 211 miles.  So quite a difference between trip computer & average mpg as calculate from brim to brim fills. (2013 MK2 Jazz 1.4 EX Plus).

About right Brian. Some people get nearer the computer - say 5% out - but 10% - give or take - is the discrepancy with this car and the 2 previous Jazzes I've owned. In fact 4 mpg over optimistic is about right and this over 12,000 miles in 3 different cars.

In fact I don't really need to do the OCD recording thing that I do. Just look at the computer calculation - deduct 4 mpg and I'm almost blob on.
Title: Re: MPG for those interested.
Post by: culzean on September 02, 2018, 10:09:55 AM
44mpg (calculated brim to brim) over the last 211 miles, mainly short journeys, although a steady cruise to Glasgow and Back along the M8 (50mpg according to trip computer for that trip). 

Trip computer showed 48.1mpg average for the 211 miles.  So quite a difference between trip computer & average mpg as calculate from brim to brim fills. (2013 MK2 Jazz 1.4 EX Plus).

About right Brian. Some people get nearer the computer - say 5% out - but 10% - give or take - is the discrepancy with this car and the 2 previous Jazzes I've owned. In fact 4 mpg over optimistic is about right and this over 12,000 miles in 3 different cars.

In fact I don't really need to do the OCD recording thing that I do. Just look at the computer calculation - deduct 4 mpg and I'm almost blob on.

The smoother your driving the closer the displayed mpg gets to real mpg, the display gets updated with a snapshot of current usage about every 10 seconds, anything that happens in time since last update (harsh acceleration etc will be ignored) this is typical of industrial 'rate' meters as well (the more you pay for them the higher the refresh / update rate). The on-board one uses the injector open times from ECU and miles on the 'A' trip to calculate mpg. The on-board display is most sensitive to change up to about 50 miles, after that it gets sluggish to register change in driving style as it averages present instantaneous use over miles on trip. I reset trip every time I fill up, that way I can see miles per half tank (rarely let tank get much less than half empty).
Title: Re: MPG for those interested.
Post by: peteo48 on September 02, 2018, 11:00:20 AM
I guess, almost by definition, stop start motoring in heavyish traffic is going to be less smooth. I was interested in this so had a look back at some manual records I used to keep before I signed up with Fuelly.com. There is no doubt that the longer trips seemed closer to the real mpg. A recorded 62.4 at one point in my 2010 Jazz was a real 58.6 (3.8 miles out). More typically the recorded mpg would be 44 and the actual 40.

That's where I got my 4 mpg out figure from. It always seemed to be 4 miles (ish) optimistic but that 4 mpg was 6% on longer trips and 10% on the stop start stuff.
Title: Re: MPG for those interested.
Post by: andruec on September 02, 2018, 05:34:55 PM
I reset trip every time I fill up, that way I can see miles per half tank (rarely let tank get much less than half empty).
Are you aware there's a function to automatically reset Trip A on refueling?
Title: Re: MPG for those interested.
Post by: culzean on September 02, 2018, 06:42:03 PM
I reset trip every time I fill up, that way I can see miles per half tank (rarely let tank get much less than half empty).
Are you aware there's a function to automatically reset Trip A on refueling?

Thanks for reminder, but it takes a five second press of sel/reset button and occasionally on longer trips I leave trip untouched and will make a note of fuel put in and mileage (and yes I know there is a B trip as well but I never use it). I leave A trip and average mpg showing all the time...
Title: Re: MPG for those interested.
Post by: zzaj on September 03, 2018, 10:06:37 AM
Are you aware there's a function to automatically reset Trip A on refueling?

How do you do that please?
Title: Re: MPG for those interested.
Post by: ColinS on September 03, 2018, 11:11:35 AM
For the MKIII it is on page 133 of the user manual:
Toggles between When Refueled, When Ignition Is Turned Off and Manual Reset
Title: Re: MPG for those interested.
Post by: andruec on September 22, 2018, 03:30:30 PM
I thought the 500 miles estimate was silly. Orange light came on at 410 miles with two bars on the fuel gauge. Finally filled up with the car saying 4 miles left, put in 35 litres. Pump to pump mpg was 55.9.

Bit of a pain. That means a full tank only has enough fuel for two week's commuting plus visiting two local golf courses..and even then I have to drive several miles with the warning light on. The sooner they fix that bridge and re-open the A422 the better :(
Title: Re: MPG for those interested.
Post by: Downsizer on September 22, 2018, 09:36:57 PM
I thought the 500 miles estimate was silly. Orange light came on at 410 miles with two bars on the fuel gauge. Finally filled up with the car saying 4 miles left, put in 35 litres. Pump to pump mpg was 55.9.
I'm very surprised you could only put in 35 litres if the miles remaining was down to 4.
Title: Re: MPG for those interested.
Post by: andruec on September 22, 2018, 09:51:39 PM
I thought the 500 miles estimate was silly. Orange light came on at 410 miles with two bars on the fuel gauge. Finally filled up with the car saying 4 miles left, put in 35 litres. Pump to pump mpg was 55.9.
I'm very surprised you could only put in 35 litres if the miles remaining was down to 4.
This whole tank has been weird. I mentioned in another thread that a closed road has resulted in me commuting by dual carriageway and motorway instead of A road. That has bumped the displayed mpg from 54 to nearly 58 and for most of the tank the car has been suggesting I'd get nearly 500 miles before filling up. Then for the final quarter it has started reducing that estimate.

At the start of today's drive to golf (21 miles each way) the gauge showed two bars and it predicted 58 miles remaining. At the start of the return journey as I pulled out of the club the fuel light came on and it was saying 27 miles remaining. Then as I pulled up to the pump at journey's end it was saying 4 miles.

It seems like some kind of correction for the overestimate at the start of the tank. Since I could only get 35 litres in (and I had to push it a bit to get that) there suggests there should have been 7 litres left which is over 70 miles of driving.

This is why I normally fill up at half or two thirds empty - to avoid this kind of fuel gauge silliness :-/
Title: Re: MPG for those interested.
Post by: culzean on September 23, 2018, 11:11:35 AM
I thought the 500 miles estimate was silly. Orange light came on at 410 miles with two bars on the fuel gauge. Finally filled up with the car saying 4 miles left, put in 35 litres. Pump to pump mpg was 55.9.
I'm very surprised you could only put in 35 litres if the miles remaining was down to 4.

It seems logical that the fuel light comes on with about 5 or 6 litres left in tank,  and once you are onto reserve fuel the 'miles to go display' is effectively in negative equity so will say zero until you fill up again.

That is why first half of tank always lasts longer than second half on any car - if tank holds 40 litres then when the gauge is on halfway mark you have used 20 litres (or maybe more if you count that there may be some extra in the tube from filler to tank, but that would be on top of normal 40 litres capacity anyway), the second half of tank will show empty and put the light on when about 14 litres have been used, the other 6 is 'reserve' - ie still there when tank is effectively empty as far as instruments are concerned.
Title: Re: MPG for those interested.
Post by: Jocko on September 23, 2018, 11:32:45 AM
Another thing I have found with my Jazz is once the fuel light comes on it stays on, until you have put sufficient fuel in to reset it. it obviously has a designed in hysteresis. Previous cars I have owned, the fuel light would start flashing on bends, or under braking, and didn't stay lit until a few miles after the first blink. My Jazz doesn't work that way. The light comes on under braking or cornering, then stays on until I fill up. It is either on longer, or is set for a much lower level.
When I went to buy the car the light was on, it was on for the extended test drive, and when the guy came to pick me up to complete the sale it was still on. About 50 miles from my first drive of the car. He then filled up on the return back to his sales room.
Title: Re: MPG for those interested.
Post by: andruec on September 25, 2018, 04:27:09 PM
Got back from my trip to North Wales (~190 miles each way plus some local travel). Crappy weather going up, good weather coming down. Car claimed 28 miles left on fill. 32 litres squeezed in. 420 miles between fills and 59mpg.

Make of that what you will :-/

As it happens Tesco Brackley only had Momentum fuel left so will be interesting to see how that performs :-/
Title: Re: MPG for those interested.
Post by: Downsizer on September 26, 2018, 10:06:05 PM
Got back from my trip to North Wales (~190 miles each way plus some local travel). Crappy weather going up, good weather coming down. Car claimed 28 miles left on fill. 32 litres squeezed in. 420 miles between fills and 59mpg.

Make of that what you will :-/

As it happens Tesco Brackley only had Momentum fuel left so will be interesting to see how that performs :-/
What was the computer showing for fuel consumption?
Title: Re: MPG for those interested.
Post by: andruec on September 26, 2018, 10:23:03 PM
Got back from my trip to North Wales (~190 miles each way plus some local travel). Crappy weather going up, good weather coming down. Car claimed 28 miles left on fill. 32 litres squeezed in. 420 miles between fills and 59mpg.

Make of that what you will :-/

As it happens Tesco Brackley only had Momentum fuel left so will be interesting to see how that performs :-/
What was the computer showing for fuel consumption?
Computer was showing just under 57mpg.

Unusual for it to be underestimating but after the drive up it was only showing 55mpg. Most of the drive up was in heavy rain so that obviously had an effect.

Interestingly the mpg is currently showing as 59.7 which is better than the previous tank. Too early to tell but that suggests better fuel consumption from Momentum.
Title: Re: MPG for those interested.
Post by: Downsizer on September 27, 2018, 05:48:46 PM
Coincidentally, I have just filled up with 32 litres after 405 miles, computer reading 59.7 mpg, actual is 57.5.  Miles remaining shown as 80 with 3 bars showing.  I think figures based on one tankful are unreliable unless you are very diligent up about "brim to brim", which I am not!
Title: Re: MPG for those interested.
Post by: nigelr on September 29, 2018, 09:15:03 AM
Interesting! I guess it depends on the roads we all drive on and prevailing traffic conditions. I live on the busy A6 and most of my driving is city / suburban, with the odd long trip. My 2013 ES manual is getting around 50mpg - I use fuelly to calculate actual fill-up MPG but the trip computer in the car isn't far off. The real benefit of the Jazz to me is that I park on a busy street and it's easy to slot into small spaces, but is big inside.
Title: Re: MPG for those interested.
Post by: Omits on October 30, 2018, 07:16:09 PM
Any vehicle for cruising you need the engine to be at the max torque which is normally 56mph. Go above that and down it goes.
Title: Re: MPG for those interested.
Post by: Skyrider on October 30, 2018, 08:13:24 PM
Any vehicle for cruising you need the engine to be at the max torque which is normally 56mph. Go above that and down it goes.

That is 5,000 rpm for the 1.3 and 4,600 rpm for the 1.5. Not the best engine revs for economy or 56 mph cruising.
Title: Re: MPG for those interested.
Post by: John Ratsey on October 30, 2018, 08:29:50 PM
Any vehicle for cruising you need the engine to be at the max torque which is normally 56mph. Go above that and down it goes.

That is 5,000rpm for the 1.3 and 4,600rpm for the 1.5. Not the best engine revs for economy or 56mph cruising.
One only has to look at the way the CVT version behaves at 56 mpg being at less than 2,000 rpm unless going up a hill. Also, last year's Land's End to John o'Groats on one tank of fuel https://www.theaa.com/about-us/newsroom/fuel-economy-record-attempt was done at a sedate 40 mph which, I'm sure, someone had figured out to be the sweet spot for best mpg. Faster would significantly increase the drag losses. 

There's also the difference between best engine efficiency and best vehicle efficiency but if our cars were more efficient at >4,000rpm in 3rd gear then why bother providing higher gears (less noise?)? I suspect that the iVTEC system messes up traditional thinking about maximum torque = best efficiency. For example, having half the inlet valves closed at lower revs improves the fuel mixing which helps efficiency at the lower rev range.
Title: Re: MPG for those interested.
Post by: andruec on October 31, 2018, 08:57:28 AM
Any vehicle for cruising you need the engine to be at the max torque which is normally 56mph. Go above that and down it goes.

That is 5,000 rpm for the 1.3 and 4,600 rpm for the 1.5. Not the best engine revs for economy or 56 mph cruising.
Well no, I'm not even sure it's possible. I'm currently commuting along the M40 and I sit in lane one with the CC set at 58mph. That's about 1,800 rpm. That'll be efficient because it's going to be running in Atkinson mode.
Title: Re: MPG for those interested.
Post by: andruec on October 31, 2018, 09:01:47 AM
Any vehicle for cruising you need the engine to be at the max torque which is normally 56mph. Go above that and down it goes.

That is 5,000rpm for the 1.3 and 4,600rpm for the 1.5. Not the best engine revs for economy or 56mph cruising.
One only has to look at the way the CVT version behaves at 56 mpg being at less than 2,000 rpm unless going up a hill. Also, last year's Land's End to John o'Groats on one tank of fuel https://www.theaa.com/about-us/newsroom/fuel-economy-record-attempt was done at a sedate 40 mph which, I'm sure, someone had figured out to be the sweet spot for best mpg. Faster would significantly increase the drag losses. 

There's also the difference between best engine efficiency and best vehicle efficiency but if our cars were more efficient at >4,000rpm in 3rd gear then why bother providing higher gears (less noise?)? I suspect that the iVTEC system messes up traditional thinking about maximum torque = best efficiency. For example, having half the inlet valves closed at lower revs improves the fuel mixing which helps efficiency at the lower rev range.
Yup. There's 'best vehicle efficiency' and there's 'extracting the most energy from a given amount of fuel'. The two can be mutually exclusive.

Driving style can be the difference between getting 30% of the energy out of the fuel (most engine efficient) and consuming 10 litres or getting 10% out and consuming 5 litres (vehicle efficient).

Oh and I forgot to update on the Momentum fuel. Inconclusive in the end. Certainly not worth the extra cost.
Title: Re: MPG for those interested.
Post by: Downsizer on October 31, 2018, 05:22:30 PM
Any vehicle for cruising you need the engine to be at the max torque which is normally 56mph. Go above that and down it goes.
Peak torque is only needed for maximum acceleration.  The beauty of CVT is that it should control engine revs to give the required power with minimum fuel consumption.  56 mph cruising could be achieved at all sorts of rpm, but only one consumes minimum fuel.
Title: Re: MPG for those interested.
Post by: peteo48 on November 03, 2018, 11:48:53 AM
8th fill up and my first sub 40 mpg figures. 39.2. Average speed only 16 mph so the cooler weather and many hours in traffic explain this one.
Title: Re: MPG for those interested.
Post by: culzean on November 07, 2018, 07:18:54 PM
https://www.aol.co.uk/2017/12/08/honda-jazz-sets-new-world-fuel-economy-record-of-95mpg/

According to this article the Honda Jazz used for record setting mpg from lands end to John o'groats on one tank ( 9 galls )  of fuel was a manual gearbox model.
Title: Re: MPG for those interested.
Post by: Pine on November 07, 2018, 07:55:09 PM
8th fill up and my first sub 40 mpg figures. 39.2. Average speed only 16 mph so the cooler weather and many hours in traffic explain this one.

Peteo,
Was your 39.2mpg taken from the on board gauge or actual fuel put in calculated against actual mileage.
Title: Re: MPG for those interested.
Post by: peteo48 on November 08, 2018, 11:51:45 AM
8th fill up and my first sub 40 mpg figures. 39.2. Average speed only 16 mph so the cooler weather and many hours in traffic explain this one.

Peteo,
Was your 39.2mpg taken from the on board gauge or actual fuel put in calculated against actual mileage.

Hi - no it was actual - brim to brim method which I record on Fuelly. If memory serves the computer was around 43 mpg.
Title: Re: MPG for those interested.
Post by: Downsizer on November 08, 2018, 01:37:14 PM
https://www.aol.co.uk/2017/12/08/honda-jazz-sets-new-world-fuel-economy-record-of-95mpg/

According to this article the Honda Jazz used for record setting mpg from lands end to John o'groats on one tank ( 9 galls )  of fuel was a manual gearbox model.
Yes - interesting.  Although the official consumption test figures show the cvt to be more economical, the John o'Groats run was no doubt under very different conditions, trying to maintain a constant speed with minimum braking and acceleration.  The official test involves frequent stops and starts.  I suppose with a manual, the driver could retain exact control of engine revs at all times, which would not be possible in a cvt.
Title: Re: MPG for those interested.
Post by: Skyrider on November 08, 2018, 01:51:54 PM
https://www.aol.co.uk/2017/12/08/honda-jazz-sets-new-world-fuel-economy-record-of-95mpg/

According to this article the Honda Jazz used for record setting mpg from lands end to John o'groats on one tank ( 9 galls )  of fuel was a manual gearbox model.
Yes - interesting.  Although the official consumption test figures show the cvt to be more economical, the John o'Groats run was no doubt under very different conditions, trying to maintain a constant speed with minimum braking and acceleration.  The official test involves frequent stops and starts.  I suppose with a manual, the driver could retain exact control of engine revs at all times, which would not be possible in a cvt.

Just shows that there is no comparison between extreme economy and real world driving.
Title: Re: MPG for those interested.
Post by: John Ratsey on November 08, 2018, 08:20:28 PM
Yes - interesting.  Although the official consumption test figures show the cvt to be more economical, the John o'Groats run was no doubt under very different conditions, trying to maintain a constant speed with minimum braking and acceleration.  The official test involves frequent stops and starts.  I suppose with a manual, the driver could retain exact control of engine revs at all times, which would not be possible in a cvt.
Also, the CVT has lower transmission efficiency than a normal gearbox (more than compensated in normal usage by the better drivetrain efficiency). I'm sure that research into the optimum speed and gear selection would have been carried out beforehand to give the confidence that the journey was feasible (it would have looked bad if they had run out of fuel at, say, Inverness). The vehicle itself had been borrowed from a dealer and hadn't been teaked. What's the engine speed in the manual 1.3 Mk 3 Jazz at 40 mph in top gear?  Well into the Atkinson cycle range.

John
Title: Re: MPG for those interested.
Post by: AlanTR on December 05, 2018, 12:39:11 PM
We have done approx. 26000 miles in our Jazz CVT and with 60/40 town/country driving - we average 48.5 to 51 mpg winter/summer with normal careful driving. These figures are as per dashboard display. Acceptable performance which does not make me feel like switching from Honda any time soon! By comparison our other car a Mk 2 Hyundai I10 (1.0 litre, 3-cylinder - an excellent manual small car) averages around 43-44 mpg (90% town driving).
Title: Re: MPG for those interested.
Post by: peteo48 on December 05, 2018, 01:51:46 PM
Just a little example of what a cold snap plus a succession of very short journeys can do. This included a few minutes in the drive with every single thing on from the air con right through to heated rear windscreen one very cold morning as we waited for the mist inside to clear. Over the 14 miles since I last filled up the computer shows the mpg at 26.7 mpg.

This will rise over the tank as longer trips factor in but it shows that, in any car, short trips and cold weather destroys mpg.
Title: Re: MPG for those interested.
Post by: andruec on December 05, 2018, 03:42:14 PM
My MPG is being dented by all the damn' traffic lights around here and the need to battle my way along minor roads. It's either that or get good MPG on the motorway but burn 50% more fuel.

Supposedly the main road I used to use for commuting should reopen before Christmas. It can't come a day too soon  >:(
Title: Re: MPG for those interested.
Post by: orcadian on December 25, 2018, 03:22:59 PM
As a newbie to the forum and to the Jazz, I have certainly found this long thread interesting and well worth reading. Although I’m in the fortunate position to be not overly concerned about fuel economy, fuel efficiency does interest me and i’m certainly interested in the question of the inaccuracies of dashboard displays and the reason why these errors might be present.  The cynic in me feels that although legal it follows the VW saga, which has been proven not to be.  I understand that the speedometer cannot legally read under the actual speed over ground but with simple software adjustments on our modern vehicles, especially with satnav, the odometer needn’t be so erroneous.

We had a 2013 Pug Partner Tepee for a couple of years and under even good long run conditions the 12500 mile countdown to service always threw the spanner light well under 9000 and that was on the odometer, the actual distance being somewhat less than that figure.  We had a trip to Austria with that car and using our Garmin separate satnav and brim to brim fill ups for 3000+ miles, the actual mpg (diesel) was a shade under 54 whereas the display indicated 59.2.
My Daimler SV8 with a 4 litre Supercharged engine, weighing in at over 2 tons and with 370 willing horses achieved a properly calculated 25.1 mpg on a recent trip to Germany, which might alarm the tree huggers but that IS fuel efficient.
By the way, I was not born cynical, it only started when I was two 🤓

Regards,
Ian



Title: Re: MPG for those interested.
Post by: culzean on December 25, 2018, 09:33:31 PM
While the display of MPG May not be entirely accurate it is a good guide to how your driving style affects MPG. The thing is the smoother your driving the more accurate the readout because if the mpg follows the same format as the industrial 'rate' meters I have had experience of they have a sample rate - the Jazz one will update the mpg reading about every 10 seconds ( you notice this more if you reset the trip), and it uses the injector ' on time' from ECU and the speed information from the ABS pulses, there can be a small error in both, it possibly uses the instantaneous information available in a register of both quantities at the 10 second mark - so a short burst of acceleration within that 10 seconds will no doubt go unnoticed by the computer.  It is also interesting that when you zero the trip the MPG indication is very sensitive as it is averaging the rate of fuel flow over only a few miles, as the trip mileage gets larger ( above 50 miles ) driving style or whether car is going up or down hill makes less difference to readout as the present rate of fuel usage is averaged out over more miles, and above 100 miles it is hard to make MPG reading change at all.  The bottom line is the display is only a guide and the smoother you drive the more accurate it will be..

Not every car has GPS info available and if you drive straight off after starting some GPS receivers take time to get a signal, so that would be another inaccuracy , and sometimes GPS signal can drop out in cities or dense forests.
Title: Re: MPG for those interested.
Post by: orcadian on December 26, 2018, 09:50:01 AM
Culzean,
Many thanks for the comprehensive reply, very informative for those who didn’t know what parameters the display  figures were derived from.  I think my issue and perhaps even the original posters issue is that when something has a tolerance, then some readouts would be high and others low (obviously not the speedo though!) so statistically if the sample was large enough then it would eventually tend towards a 50/50 split.

The technology is clearly there for the manufacturers to bring the displayed readout somewhere closer to reality, but that is obviously not in their interests.
Hope you all had a good one,
Cynically yours,
Ian
Title: Re: MPG for those interested.
Post by: peteo48 on December 26, 2018, 10:58:39 AM
I've found virtually every one of my recent cars - ie those fitted with an mpg indicator - have exaggerated  mpg by between 5 and 10 %. In recent years it's always been about 4 mpg. In support of Culzean's arguments driving style is most definitely a factor. Most of my driving these days is short stop start stuff with a lot of acceleration and then deceleration in an engine that only gets up to operating temperature as we pull into the supermarket car park!

My avatar shows an average mpg of 43.8 (actual as opposed to indicated) and this is over just under 2,000 miles. Trip B which I never change is showing an mpg of dead on 48. Looking back in my records, the odd long trip where you are cruising for most of the time brings the computer much closer to the actual in percentage terms.

Being a bit OCD I faithfully do the brim to brim method and record the results on Fuelly.com but, to be honest, I would get a decent working figure by just looking at the computer figure and deducting 4 mpg.
Title: Re: MPG for those interested.
Post by: mikebore on December 26, 2018, 12:01:54 PM
Similar to my experience, except

1. My Fuelly number is 46.1mpg over 36,000 miles (fair amount of long journeys).

2. My computer to Fuelly difference is more like 2-5 mpg, but usually close to 4. When I get a big or small difference I suspect variability in top off procedure when filling, and pump to pump cut off variability.
Title: Re: MPG for those interested.
Post by: orcadian on December 26, 2018, 12:31:37 PM
Interesting Peteo that you can do it accurately over a period of time, OR just deduct 4 mpg from the computer readout which is exactly my point - the manufacturers could do that!
Wonder if anyone has ever got MORE mpg than the display indicated? It would not surprise me if no one had.

Ian
Title: Re: MPG for those interested.
Post by: ColinB on December 26, 2018, 12:42:21 PM
I've taken to monitoring the "current drive" page on the big screen rather than just Trip A or B. On a longish drive on fast A roads or motorways it's not unusual to see an MPG for that drive of over 60, but for a short journey around town only around 25. Those figures are probably optimistic, but I don't expect absolute accuracy but rather an  indication of whether I'm driving efficiently. Plus you can easily see the range reading on the same page and watch that fluctuate wildly (recently I saw it veer from 390 down to 370 and back up to 470 all in the space of around 10 miles whilst driving at a reasonably constant speed !)
Title: Re: MPG for those interested.
Post by: John Ratsey on December 26, 2018, 12:48:52 PM
The computer on my hybrid Jazz was about 5% optimistic while the Mk 3 Jazz was at least 7% high. In contrast, my current HR-V is only about 3% optimistic. I have to wonder if Honda put bigger a fudge factor in the Mk. 3 Jazz's computations so that people would get closer to the claimed mpg and more than the Mk. 2. The HR-V, in contrast, had no recent preceding model over which it needs to show an improvement.

I've never checked the Odometer for accuracy. There's no real reason for it to have any error greater than that caused by tyre wear which will cause an apparent increase in distance of up to 2% in which case new tyres could have up to 2% worse apparent mpg than worn ones.
Title: Re: MPG for those interested.
Post by: orcadian on December 26, 2018, 01:25:34 PM
That’s a very interesting point John about no recent previous model comparison, so we are gradually converging on ‘codology’ by manufacturers, which surprises none of us methinks.  This is obviously not aimed at just Honda but many people still believe these readouts and often brag about them on other less well informed forums.

Ian
Title: Re: MPG for those interested.
Post by: peteo48 on December 26, 2018, 05:31:14 PM
I agree, Ian, people do, wrongly, believe the computer figure. This obviously works in the manufacturers favour.

Is it actually, technically, possible to produce an accurate figure via an onboard computer? I don't have the technical knowledge to answer that.
Title: Re: MPG for those interested.
Post by: orcadian on December 26, 2018, 06:24:16 PM
No Peteo, I don’t think it’s possible to get a consumption figure to be exact for many of the reasons already outlined by previous posters but as most folk have discovered, if the computer figure is always higher, then it’s certainly possible for manufacturers to get closer to reality.  Don’t hold your breath til they do it though!  I can’t believe some smart Alec Philadelphia Lawyer hasn’t tried yet.

It’s only a bit of fun for me and as many have correctly said it does indicate how you are driving and the CHANGE in overall consumption on your own particular vehicle is more important that the fictitious readout.

Ian
Title: Re: MPG for those interested.
Post by: andruec on December 26, 2018, 07:27:45 PM
Just got back from a trip to see my Dad. 424 miles, mostly motorway at ~60mph with cruise control. Also mostly at night so headlights on. Two bars and a claimed 54 miles left according to the dash display. 33 litres put in.

Just over 58mpg.
Title: Re: MPG for those interested.
Post by: culzean on December 26, 2018, 08:21:26 PM
According to Honest John Honda in general are one of the closest to true MPG with their claimed MPG. Some makers tell proper porkies with their astronomical claims......

https://www.honestjohn.co.uk/real-mpg/
Title: Re: MPG for those interested.
Post by: peteo48 on December 27, 2018, 10:44:49 AM
Just got back from a trip to see my Dad. 424 miles, mostly motorway at ~60mph with cruise control. Also mostly at night so headlights on. Two bars and a claimed 54 miles left according to the dash display. 33 litres put in.

Just over 58mpg.

Great figures. My record is a tad over 56 in my Mk2. In summer that 58 might well have been 60.
Title: Re: MPG for those interested.
Post by: andruec on December 27, 2018, 02:09:49 PM
Just got back from a trip to see my Dad. 424 miles, mostly motorway at ~60mph with cruise control. Also mostly at night so headlights on. Two bars and a claimed 54 miles left according to the dash display. 33 litres put in.

Just over 58mpg.

Great figures. My record is a tad over 56 in my Mk2. In summer that 58 might well have been 60.
Oh I did better than that once (https://clubjazz.org/forum/index.php?topic=7808.msg40927#msg40927) :)

If I remember correctly toward the end of some roadworks on the M6 the dash displayed 79.8mpg. I was probably the only driver wishing the 50mph limit continued for a couple more miles :)

Title: Re: MPG for those interested.
Post by: peteo48 on January 03, 2019, 03:00:30 PM
Just had my lowest mpg figures for over 2 years - 33.8 mpg (36.1 on computer). Lots of very short journeys and, of course, the cold. Average speed of 13 mph shows how stop start in the cold destroys mpg on any car.
Title: Re: MPG for those interested.
Post by: andruec on January 03, 2019, 03:18:56 PM
Just had my lowest mpg figures for over 2 years - 33.8 mpg (36.1 on computer). Lots of very short journeys and, of course, the cold. Average speed of 13 mph shows how stop start in the cold destroys mpg on any car.
Temperature is an interesting one. I've no recorded figures to back this up but it seems like the Mk3 is more sensitive to temperature (or at least environmental) changes than previous models. From what I recall my previous two Jazz (Mk1, Mk2) varied by only a couple of MPG. I think the Mk2 was ~51mpg in summer, and ~49mpg in winter. My Mk3 is ~56mpg in summer and ~50mpg in winter.

I don't have any recorded figures to back this up however. It's just a feeling and is based off the dashboard display rather than fill-to-fill figures.
Title: Re: MPG for those interested.
Post by: Downsizer on January 04, 2019, 09:44:43 PM
Temperature is an interesting one. I've no recorded figures to back this up but it seems like the Mk3 is more sensitive to temperature (or at least environmental) changes than previous models. From what I recall my previous two Jazz (Mk1, Mk2) varied by only a couple of MPG. I think the Mk2 was ~51mpg in summer, and ~49mpg in winter. My Mk3 is ~56mpg in summer and ~50mpg in winter.
[/quote]
Seven years ago I posted these figures.  I must have a look at how the Mk 3 compares.
"Taking winter as October to March inclusive, and based on total fuel bought and total mileage over 3+ years, I find the winter average for a 1.4 ES manual is 46.8 mpg over 14777 miles, with the summer giving 49.3 mpg over 14481 miles.  Overall average 48.0 mpg"
Title: Re: MPG for those interested.
Post by: John Ratsey on January 04, 2019, 10:19:21 PM
Put the trip mpg on the touchscreen display and watch it increase as the engine warms up. I reckon that my HR-V takes about 10 miles to properly warm up in cold weather. Thermostatically controlled louvres on the front of the engine compartment would improve the cold weather performance but manufacturers will have no incentive to provide these or other measures to shorten the warm-up period unless cold starts are part of the standard economy tests. If the conditions permit (ie no window demist need) I leave the cabin heating off for the first couple of miles so that water in the engine can warm up a bit faster.
Title: Re: MPG for those interested.
Post by: andruec on January 04, 2019, 10:27:17 PM
Put the trip mpg on the touchscreen display and watch it increase as the engine warms up. I reckon that my HR-V takes about 10 miles to properly warm up in cold weather.
Sounds about right. My commute is ~12 miles and the MPG display doesn't start to 'recover' after a cold start until I'm within a couple of miles of my destination.
Title: Re: MPG for those interested.
Post by: John A on January 05, 2019, 11:23:16 AM
I've got a voltage display from the cigarette socket and what I do notice in the colder weather is that the voltage stays up around 14.2v much more of the time compared when it's warm outside, and when it's
warm it'll indicate the batteries voltage more often. Extra power will be needed, which might help explain some of the reduced mpg in colder weather.
Title: Re: MPG for those interested.
Post by: Downsizer on January 05, 2019, 03:17:52 PM
I've now compared winter and summer consumption in my nearly 3yr-old Mk 3.  In 18 summer months I covered 15991 miles using 1391 litres, giving 52.3 mpg.  In 16 winter months I covered 13276 miles using 1193 litres, giving 50.6 mpg, about 3% lower.  This compares with a difference of 5% in the Mk 2, but I don't think this is significant based on a sample of only one user!  It is clear however that the MK 3 is more economical overall, as reported by many users.
Title: Re: MPG for those interested.
Post by: Jeangenie on February 14, 2019, 09:40:38 AM
First fill up with my new Jazz Sport and it managed 38.7 mpg. Better than my Fiesta which rarely bettered 36.
Title: Re: MPG for those interested.
Post by: Jocko on February 14, 2019, 10:10:57 AM
I would have hoped for a bit better than that, even with the 1.5L engine. Mind you, the fact it is brand new, with the tyres barely having the pimples rubbed off, and your daily commute into and out of the city, probably not a bad figure.
Is that calculated or from the dashboard display?
Title: Re: MPG for those interested.
Post by: peteo48 on February 14, 2019, 11:12:22 AM
On mpg more generally I asked my neighbour what he gets out of his Mk3 Jazz (67 plate, 1.3 CVT EX) and he is delighted that he gets an indicated 35 (32 ish probably in real life). Seems bad but he got 30 out of his Civic and 26 out a Focus 1.8 that he had before that. His driving profile is even more short distance and town/stop/start that mine. He almost never drives more than 5 miles and a typical trip is to Sainsburys - about 4 miles return in heavyish traffic. Unlike me he never does the occasional longer trip.

Driving style is very important but the type of journey is the overwhelming factor. If, like me and my neighbour, your car rarely gets to full operating temperature, the mpg will be crap whatever you drive.

Ironically, EVs thrive on the type of motoring that destroys mpg in ICE cars because of the low speeds and regen braking.
Title: Re: MPG for those interested.
Post by: mikebore on February 14, 2019, 11:48:01 AM
Any one got any real world, real measurement comparison of the latest 1.5 non-Atkinson with the 1.3 Atkinson?
Title: Re: MPG for those interested.
Post by: Jeangenie on February 14, 2019, 02:37:15 PM
I do 50 miles a day to and from Edinburgh so the car gets pretty hot. The mpg figure is from the display. I never bother working the numbers out. I have to do the miles so I have to use the petrol and the dashboard display is near enough for my curiosity.
Title: Re: MPG for those interested.
Post by: peteo48 on February 14, 2019, 04:25:46 PM
I think it will get better, as Jocko implied, as the car settles in and the weather gets warmer.
Title: Re: MPG for those interested.
Post by: Barky on February 14, 2019, 06:44:47 PM
Getting an indicated 48.5 to 50 mpg on rural hilly roads on a 20 mile each way regular commute .... with a bit of careful driving & reaching flatter roads I'm sure 55 should be within easy reach  8)
Title: Re: MPG for those interested.
Post by: andruec on February 14, 2019, 09:07:45 PM
I don't often calculate it precisely but when filling up I expect better than 10:1 (miles:litres = 45mpg). So if I've driven 340 miles I expect to put a bit less than 34 litres in. So far I've always been better than 10:1.

Most of my driving is on main roads. My commute is 12 miles each way and includes a couple of miles in the evening that can be stop/start but mostly it's a steady 50mph. I also drive to local golf courses so that's mostly open road as well.
Title: Re: MPG for those interested.
Post by: John Ratsey on February 15, 2019, 10:14:32 AM
I do 50 miles a day to and from Edinburgh so the car gets pretty hot. The mpg figure is from the display. I never bother working the numbers out. I have to do the miles so I have to use the petrol and the dashboard display is near enough for my curiosity.
You might want to do some checks. I had a Mk. 3 Jazz for a year and the computer was 9% optimistic compared with the mpg calculated from fuel used and miles travelled. However, I don't recall any other Mk. 3 Jazz owners reporting similarly large discrepancies. However, the overall check compared with your previous car is whether the weekly fuel bill goes up or down (although the oscillations in the petrol price add some confusion to this approach).
Title: Re: MPG for those interested.
Post by: mikebore on February 15, 2019, 11:38:14 AM

I had a Mk. 3 Jazz for a year and the computer was 9% optimistic compared with the mpg calculated from fuel used and miles travelled. However, I don't recall any other Mk. 3 Jazz owners reporting similarly large discrepancies.

This is typical of my Mk3.
Title: Re: MPG for those interested.
Post by: peteo48 on February 15, 2019, 12:45:29 PM
9% is about the discrepancy I've noticed over 2 Mk2 Jazzes and my current Mk3. It always seems to end up as about 4 mpg over optimistic. The only time it is more accurate in percentage terms is on long journeys so a recorded 60 will be an actual 56 but it's always 4 mpg!

Indeed, at the moment, the computer is showing 46.4 mpg over the 2500 or so miles since I've had the car and this is an actual 42.4 (see my avatar).
Title: Re: MPG for those interested.
Post by: Downsizer on February 16, 2019, 03:43:45 PM
I've just completed 3 years and 30636 miles, using 2738 litres of mainly ASDA 95, giving 50.9 mpg.  Trip B has been running throughout without resetting and is showing 55.8 mpg, a discrepancy of 9%.  Average speed shown as 35 mph.
Title: Re: MPG for those interested.
Post by: peteo48 on February 16, 2019, 03:59:26 PM
I've just completed 3 years and 30636 miles, using 2738 litres of mainly ASDA 95, giving 50.9 mpg.  Trip B has been running throughout without resetting and is showing 55.8 mpg, a discrepancy of 9%.  Average speed shown as 35 mph.

Good figures. My average speed is 18 mph which accounts for my low mpg. I'm pretty sure I'd be in the 50 plus bracket if I was still doing my old 30 mile round trip commute to work.
Title: Re: MPG for those interested.
Post by: Jocko on February 16, 2019, 04:07:08 PM
Good numbers. Well done.
Title: Re: MPG for those interested.
Post by: mikebore on February 16, 2019, 04:54:19 PM
Fuelly is giving 46.0 avg for 37974 miles since I got the car new 32 months ago.

I haven't recorded average speed or the computer numbers but computer usually about 4mpg higher.

I am pretty sure that trip B reset every 10000 miles on my mark 2. Not bothered with it on mk3. Is your trip B showing the full 30636 miles?
Title: Re: MPG for those interested.
Post by: Downsizer on February 16, 2019, 06:48:36 PM
Fuelly is giving 46.0 avg for 37974 miles since I got the car new 32 months ago.

I haven't recorded average speed or the computer numbers but computer usually about 4mpg higher.

I am pretty sure that trip B reset every 10000 miles on my mark 2. Not bothered with it on mk3. Is your trip B showing the full 30636 miles?
No. Trip B has only 4 digits, but it seems that the average speed and fuel calculations continue unbroken.  I paid particular attention when it recently passed 9999 for the third time, and the averages didn't change.  Much of my driving is in East Anglia and north up the A1, which is all relatively flat.   No doubt this helps the fuel economy.  At the recent service, in a moment of weakness I was persuaded to pay £35 for a Tunap cleaner and additive treatment, but I'm not expecting any miraculous improvements!
Title: Re: MPG for those interested.
Post by: mikebore on February 16, 2019, 07:10:37 PM
Thanks! Useful to know that average speed and mpg of trip B do not reset.
Since I have never reset my trip B the mpg and speed should be correct data for my 38000 miles? Can't look at the moment
Title: Re: MPG for those interested.
Post by: Jeangenie on February 20, 2019, 09:19:56 AM
Last night's top up showed 41.1 mpg so a big improvement. I am happy with that. Next week my husband and I will be swapping cars so it will be interesting to see what sort of figure he gets.
Title: Re: MPG for those interested.
Post by: Jocko on February 20, 2019, 09:29:34 AM
That's better. If Bill is anything like his dad he will make a competition out of next week's figures! Willie was always very competitive.
Title: Re: MPG for those interested.
Post by: mikebore on February 23, 2019, 07:28:34 AM
Thanks! Useful to know that average speed and mpg of trip B do not reset.
Since I have never reset my trip B the mpg and speed should be correct data for my 38000 miles? Can't look at the moment

I have auto reset on tank fill set and it seems to reset B as well as A so I can't see my data for all 38000.
Title: Re: MPG for those interested.
Post by: John A on February 23, 2019, 12:42:01 PM
Thanks! Useful to know that average speed and mpg of trip B do not reset.
Since I have never reset my trip B the mpg and speed should be correct data for my 38000 miles? Can't look at the moment

I have auto reset on tank fill set and it seems to reset B as well as A so I can't see my data for all 38000.

I know my Mk 3 has various options for resetting A and B and am sure that the Mk2 I had was the same. I use A to reset on refuel and B for ignition on / off.
Title: Re: MPG for those interested.
Post by: mikebore on February 23, 2019, 02:22:46 PM
Thanks! Useful to know that average speed and mpg of trip B do not reset.
Since I have never reset my trip B the mpg and speed should be correct data for my 38000 miles? Can't look at the moment

I have auto reset on tank fill set and it seems to reset B as well as A so I can't see my data for all 38000.

I know my Mk 3 has various options for resetting A and B and am sure that the Mk2 I had was the same. I use A to reset on refuel and B for ignition on / off.

Thanks that would be good...I will have another look. I know on my Mk2 I could have A and B different settings and when I got the Mk3 was surprised and disappointed that it was different...but maybe user error. I think we had a thread about it back then.

https://clubjazz.org/forum/index.php?topic=8210.msg40747#msg40747 (https://clubjazz.org/forum/index.php?topic=8210.msg40747#msg40747) is the thread. It confirms what you say that they can be set independently...I had forgotten.
Title: Re: MPG for those interested.
Post by: Jeangenie on February 25, 2019, 09:07:15 AM
Filled up yesterday and the display said 40.4 mpg. I am more than happy with that. My husband is using my Jazz this week so we will see what mpg he can get. I have his Type R today and what a brute. He told me to leave it in Comfort mode not that I will mess about with things. Not the best experience in Edinburgh morning rush hour traffic.
Title: Re: MPG for those interested.
Post by: Jeangenie on February 27, 2019, 07:35:40 AM
My husband has been using my Jazz Sport this week and filled up last night. Display said 51.1 mpg but he calculated the true figure and it was 49.7 mpg. I don't know how he does it. The display on his car which I am using is currently showing 19.5 mpg!
Title: Re: MPG for those interested.
Post by: Jocko on February 27, 2019, 08:03:55 AM
You have a fair bit of catching up to do!
Title: Re: MPG for those interested.
Post by: Downsizer on February 27, 2019, 09:12:15 AM
My husband has been using my Jazz Sport this week and filled up last night. Display said 51.1 mpg but he calculated the true figure and it was 49.7 mpg. I don't know how he does it. The display on his car which I am using is currently showing 19.5 mpg!
Presumably your husband has longer runs at steadier speeds, with fewer stops and starts?
Title: Re: MPG for those interested.
Post by: peteo48 on February 27, 2019, 10:42:41 AM
My husband has been using my Jazz Sport this week and filled up last night. Display said 51.1 mpg but he calculated the true figure and it was 49.7 mpg. I don't know how he does it. The display on his car which I am using is currently showing 19.5 mpg!

It might be ungallant to say it but is your right foot a tad heavier ;)
Title: Re: MPG for those interested.
Post by: mikebore on February 27, 2019, 11:02:11 AM
My husband has been using my Jazz Sport this week and filled up last night. Display said 51.1 mpg but he calculated the true figure and it was 49.7 mpg. I don't know how he does it. The display on his car which I am using is currently showing 19.5 mpg!

It might be ungallant to say it but is your right foot a tad heavier ;)

Or if the setting is "reset on tank fill" it might just be that it had only just been filled up. That is the only time I see very low numbers, or if Jean is looking at the current trip on the infotainment screen.
Title: Re: MPG for those interested.
Post by: andruec on February 27, 2019, 01:53:54 PM
My husband has been using my Jazz Sport this week and filled up last night. Display said 51.1 mpg but he calculated the true figure and it was 49.7 mpg. I don't know how he does it. The display on his car which I am using is currently showing 19.5 mpg!

It might be ungallant to say it but is your right foot a tad heavier ;)
Or using the break pedal for other than actually bringing the vehicle to a halt. So many people think that there's one pedal to make the car go faster and different one to reduce the speed.
Title: Re: MPG for those interested.
Post by: Jeangenie on February 27, 2019, 07:33:35 PM
Presumably your husband has longer runs at steadier speeds, with fewer stops and starts?
My husband does considerably more miles with most of it in lighter faster moving traffic.
Title: Re: MPG for those interested.
Post by: Jeangenie on February 27, 2019, 07:35:31 PM
it might just be that it had only just been filled up. That is the only time I see very low numbers.
I had done about 150 miles since topping up. I have now done 190 miles and it is reading 19.8 mpg. At this rate I should see it over 20 by the time I have to fill up at the weekend
Title: Re: MPG for those interested.
Post by: Jeangenie on February 27, 2019, 07:38:15 PM
Or using the break pedal for other than actually bringing the vehicle to a halt. So many people think that there's one pedal to make the car go faster and different one to reduce the speed.
I do 30 miles a day in stop start queueing traffic so it pretty much is a case of one pedal or the other.
The Type R is not a car for daily rush hour commuting to and from the city centre!
Title: Re: MPG for those interested.
Post by: andruec on February 27, 2019, 08:20:09 PM
Or using the break pedal for other than actually bringing the vehicle to a halt. So many people think that there's one pedal to make the car go faster and different one to reduce the speed.
I do 30 miles a day in stop start queueing traffic so it pretty much is a case of one pedal or the other.
The Type R is not a car for daily rush hour commuting to and from the city centre!
That makes it more difficult but allowing a gap to open up to the vehicle in front ought to allow you to minimise the need for brakes. A few months ago I was having to commute via J10 of the M40 which meant fifteen to twenty minutes in a queue of cars and I rarely needed the brakes. Instead of stop/start try and just inch along at the average speed.
Title: Re: MPG for those interested.
Post by: peteo48 on March 02, 2019, 11:17:00 AM
An annual report on my Mk 3 1.3 SE CVT Jazz.

I've now had it a year (just over in fact) but I can report the following:

1) Annual Miles 2,362 (lower than normal but no UK holiday this year).
2) Daily average miles - 6.47.
3) Average speed 18 mph.
4) Lowest mpg - 33.8 (actual not computer)
5) Highest mpg - 50.1
6) 80% City Driving (equivalent to old NEDC Urban Cycle - 20% at Extra Urban)
7) Computer out by exactly 4.2 mpg - Average MPG is 42.2 - computer says 46.4

So, how does this compare with my previous Mk 2s. I have excluded my last Mk2 because it did some long journeys including a period where I was driving 75 miles a day to have radiation treatment. More typical was my first Mk2 which averaged exactly 40 mpg over very similar driving conditions. The MK3 shows a 5% improvement in mpg although I suspect it has had fewer longish trips.

I'm quite happy with these figures. A typical job for my car is a 4 mile return trip to the supermarket. I probably rarely, if ever, get to a decent operating temperature.
Title: Re: MPG for those interested.
Post by: Jeangenie on March 02, 2019, 06:50:43 PM
Hubby filled the Jazz up today before swapping back and he got an indicated 53.3 mpg and a calculated 51.8 mpg.
He thinks it a pleasant comfortable car to drive but grossly underpowered for a Sport. He says it needs a turbo or a bigger engine. 1.5 litres is not enough.
I had to fill up the Type R yesterday morning and the display said 21.4 mpg. I had to top it off again today before passing it back and the display said 18.7 mpg. Mind you it was only for 65 miles.
I am glad I do not have to put Shell V Power in mine. The price per litre is terrible.
Title: Re: MPG for those interested.
Post by: Jocko on March 02, 2019, 06:55:10 PM
You could have got 97 RON in Morrisons. Nowhere near as expensive as the V-Power.
Title: Re: MPG for those interested.
Post by: peteo48 on March 03, 2019, 11:20:09 AM
Yes - the supermarket high octane fuels only have a 5p mark up over the 95 unleaded. The brands charge at least 10 p a litre more for high octane stuff.
Title: Re: MPG for those interested.
Post by: peteo48 on April 15, 2019, 11:57:30 AM
Just recorded my record mpg so far in the Mk 3 - 52.6 actual (showed as 54.9 on the computer). Quite happy with this as it included a recent round trip of 220 miles with 3 adults and luggage in the car and also cruising a lot of the time at 70 mph.
Title: Re: MPG for those interested.
Post by: Jocko on April 15, 2019, 12:39:26 PM
Those are good numbers. Particularly at this time of year. The same journey, in the summer, would have been even better.
Title: Re: MPG for those interested.
Post by: andruec on April 16, 2019, 09:33:37 PM
Just thought I'd drop by to give you the figures for my first two tanks with my Corolla hybrid. 56 and 58 at the pump (reported as 58 and 59 by the car). My Jazz was turning in around 50 mpg at the pump for comparison when I sold it.

I'm pretty sure I could do better because at the moment I'm being lazy and using the adaptive cruise control virtually all the time. Although it uses EV mode some of the time I know a few places where I could get it into EV mode a bit earlier. Got my first long motorway drive next week so will be interesting to see how it does. My Jazz would get me over 60mpg on my trips to North Wales and that's going to be tough to beat - basically a fight between a 1.3 litre engine in Atkinson mode and a 1.8 litre in Atkinson mode. It does use the battery power occasionally at 60 mph and cruises at less than 1,500 rpm but I don't know if it will be enough to return a better figure.

I'll be very interested to see the figures for the new Jazz Hybrid when it finally arrives.
Title: Re: MPG for those interested.
Post by: John Ratsey on April 17, 2019, 06:32:07 PM
I'm pretty sure I could do better because at the moment I'm being lazy and using the adaptive cruise control virtually all the time. Although it uses EV mode some of the time I know a few places where I could get it into EV mode a bit earlier. Got my first long motorway drive next week so will be interesting to see how it does. My Jazz would get me over 60mpg on my trips to North Wales and that's going to be tough to beat - basically a fight between a 1.3 litre engine in Atkinson mode and a 1.8 litre in Atkinson mode. It does use the battery power occasionally at 60 mph and cruises at less than 1,500 rpm but I don't know if it will be enough to return a better figure.
My guess is that for sustained cruising at 60 mph or above your Corolla will pull ahead on mpg as it sits lower on the road and should be aerodynamically better than the Jazz by a big enough margin to offset any deadweight due to the hybrid system. Cruising at 50 or below probably sees the Jazz pull ahead. Don't forget the Land's End to John O'Groats run by the Mk 3 Jazz - very impressive mpg at a sustained 40 mph. Hybrids best deliver their benefit in variable speed motoring.
Title: Re: MPG for those interested.
Post by: andruec on April 17, 2019, 07:09:44 PM
I'm pretty sure I could do better because at the moment I'm being lazy and using the adaptive cruise control virtually all the time. Although it uses EV mode some of the time I know a few places where I could get it into EV mode a bit earlier. Got my first long motorway drive next week so will be interesting to see how it does. My Jazz would get me over 60mpg on my trips to North Wales and that's going to be tough to beat - basically a fight between a 1.3 litre engine in Atkinson mode and a 1.8 litre in Atkinson mode. It does use the battery power occasionally at 60 mph and cruises at less than 1,500 rpm but I don't know if it will be enough to return a better figure.
My guess is that for sustained cruising at 60 mph or above your Corolla will pull ahead on mpg as it sits lower on the road and should be aerodynamically better than the Jazz by a big enough margin to offset any deadweight due to the hybrid system. Cruising at 50 or below probably sees the Jazz pull ahead. Don't forget the Land's End to John O'Groats run by the Mk 3 Jazz - very impressive mpg at a sustained 40 mph. Hybrids best deliver their benefit in variable speed motoring.
Yeah, I have driven a few relatively short sections of MWay/DC at 60mph and it was interesting to see how 'active' the system was in mixing the two power sources. A lot of people think that the hybrid stuff is all or nothing but actually it's forever swapping between sources and often combines them.

I can just about see that if it can cruise at 60mph at <1,500 rpm and it comes to a slight incline it might make sense to utilise the battery rather than increase the RPMs. Of course the battery energy is not free(*) so eventually it has to increase the engine RPMs above what's needed for cruising in order to recharge. But perhaps (and these are made up numbers) it goes something like:

Climbing an incline with battery+engine@1500 followed by engine@2000 temporarily to recharge saves more fuel than climbing the incline at 2500rpm.

And of course most inclines are followed by a decline which will help improve the advantage further.

One thing I've noticed is the performance difference. From stationary and at low speed the Corolla would leave a Jazz in the dust. It's actually quite 'scary' just how much get up and go you get when it's an electric motor doing the work. At higher speeds there's little to nothing in it and in fact I think that in 'normal' mode at least the Jazz might have the edge. In 'power' mode possibly not but it seems that a 1.3 l engine operating on the Otto cycle outguns a 1,8 l engine operating on the Atkinson cycle and the battery can only help overcome that for a while.

(*)In fact several experts say that trying to run in EV mode as much as possible is actually not the best strategy. The system is around 80% efficient so they say that the car should be left to mix/match as it sees fit rather than trying to play the 'I'm an electric car' game.
Title: Re: MPG for those interested.
Post by: Downsizer on April 18, 2019, 05:05:56 PM
My guess is that for sustained cruising at 60 mph or above your Corolla will pull ahead on mpg as it sits lower on the road and should be aerodynamically better than the Jazz by a big enough margin to offset any deadweight due to the hybrid system. Cruising at 50 or below probably sees the Jazz pull ahead. Don't forget the Land's End to John O'Groats run by the Mk 3 Jazz - very impressive mpg at a sustained 40 mph. Hybrids best deliver their benefit in variable speed motoring.
The only drag figures I've been able to find suggest coefficients of 0.30 for the new Corolla, and 0.33 for the Mk 3 Jazz/Fit.  Drag increases as the square of speed, so as you suggest, the Corolla should be more fuel efficient at higher speeds.  It's an interesting comparison in anticipation of a Jazz hybrid.  I'm not yet convinced that non plug-in hybrids achieve much in overall economy, but they should be cleaner in urban areas in electric mode.
Title: Re: MPG for those interested.
Post by: andruec on April 18, 2019, 07:40:51 PM
I'm not yet convinced that non plug-in hybrids achieve much in overall economy, but they should be cleaner in urban areas in electric mode.
They definitely achieve a lot better economy in urban/extra urban use. My daily commute is 9 miles free running A road and 2 miles busy town. I was getting ~50mpg in my Jazz when I sold it a month ago and am getting ~58mpg in the Corolla. And that figure for the Corolla is a new, tight engine.
Title: Re: MPG for those interested.
Post by: peteo48 on August 01, 2019, 12:41:03 PM
I'm always cautious about the debate over high octane or super fuels and I'm not sure what to read into my latest refill which is the third consecutive refill after using 97 or 98 Octane.

But here's the thing. I filled up today on Sainsburys 97 RON after 189 miles on Apple Green 97 RON and that followed on from a tank of 97 RON from Sainsburys. The average speed was 16 mph and, for a large chunk of that 189 miles I've been travelling, in rush hour traffic to feed my daughters pets whilst she was on holiday. I also had some real crawling motoring when attending and leaving the RHS Tatton Flower Show a fortnight ago.

Yes it's been warm but I have also driven through heavy rain - a lot of standing water. This last refill shows an mpg of 45.5 - I've never had this sort of mpg after driving in heavy traffic. I would have expected around 42 tops.

Early days but I am starting to be convinced that there are gains to be had from using the higher octane fuel in the Mk3 Jazz which does, of course, have a very high CR. I am also sensing a slight improvement in responsiveness.

I'll report further on this. Given fuel costs are a minor consideration for me due to the low annual mileage I do (less than 3000 in 2018) I tempted to stay on the higher octane stuff for a few more tanks at least.
Title: Re: MPG for those interested.
Post by: Kenneve on August 01, 2019, 04:17:20 PM
The figures you quote represent an increase in MPG of 8.3% I guess an average the cost difference of Super-unleaded fuel is in the order of 12%, so that gives a real increase of probably less than 4%, which is easily accountable with traffic conditions, style of driving and/or performance, Stick with the Super fuel!!
Title: Re: MPG for those interested.
Post by: Downsizer on August 02, 2019, 10:49:25 AM
Re super fuel, I seem to remember someone suggesting previously that the variable valve timing would in some way detect the higher octane fuel and in effect adjust the compression ratio accordingly.  I have some doubts about this, but it's an interesting idea - does anyone knows more about it?
Title: Re: MPG for those interested.
Post by: Jocko on August 02, 2019, 11:48:49 AM
It is not the variable valve timing but the knock sensor that allows the ignition to be advanced some, with "super" fuels.
Title: Re: MPG for those interested.
Post by: mikebore on August 02, 2019, 12:01:16 PM
It is not the variable valve timing but the knock sensor that allows the ignition to be advanced some, with "super" fuels.

For many years I was firmly in the camp that believe if the octane is high enough to prevent knocking there is no benefit for higher octane. But the advent of knock detection and automatic ignition advance to the point where it is just not knocking, gives a technical basis why higher octane might be more efficient, or more powerful.

However I have never seen any convincing data supporting this. There are lots of reports by people who know which fuel they are using and therefore tend believe they notice a difference. I have used Shell 99 sometimes and don't believe I could tell which fuel was in the tank by power or economy.
Title: Re: MPG for those interested.
Post by: culzean on August 02, 2019, 12:02:21 PM
Re super fuel, I seem to remember someone suggesting previously that the variable valve timing would in some way detect the higher octane fuel and in effect adjust the compression ratio accordingly.  I have some doubts about this, but it's an interesting idea - does anyone knows more about it?

From what I have read about modern direct injection engines, particularly Honda and Mazda they avoid knocking at lower revs by injecting the fuel when compression stroke nearly at top dead centre ( if you are only compressing air it does not matter if it heats up ). I read that Honda DI nozzle is centrally located in cylinder head, and at lower revs actually injects fuel at over 40:1 ratio into a bowl in the piston crown - at higher revs the fuel map changes and he fuel is injected on intake stroke at 14.5:1 ratio.  So on direct injection engines even though some over 13:1 compression ratio knocking is dealt with by the way fuel is injected.

The Civic 1.8 ivtec engine has had variable compression ratio controlled by late closing of inlet valves at lower revs since 2006 ( thus mimicking the mechanical stroke variation in a 'proper' Atkinson cycle engine without all the complication ) but not direct injection at that time, could not comment on whether the detection of knocking by the normal sensors affects the closing point of inlet valves but I doubt it.
Title: Re: MPG for those interested.
Post by: peteo48 on August 02, 2019, 12:09:19 PM
On improved mpg, I spent a geeky half hour recently looking at Greenergy's fuel quality reports. They do one a month for each fuel they sell. It is clear that the high octane stuff is more dense. Could this have anything to do with it?
Title: Re: MPG for those interested.
Post by: culzean on August 02, 2019, 12:21:14 PM
On improved mpg, I spent a geeky half hour recently looking at Greenergy's fuel quality reports. They do one a month for each fuel they sell. It is clear that the high octane stuff is more dense. Could this have anything to do with it?

There is actually less energy in higher octane fuel because of the octane boosters which are there to delay detonation, ethanol used as an octane booster has a fair bit less energy than the petrol.
Title: Re: MPG for those interested.
Post by: peteo48 on August 02, 2019, 12:25:01 PM
From what I could tell the ethanol content was the same in each grade. I'll double check.
Title: Re: MPG for those interested.
Post by: culzean on August 02, 2019, 12:28:23 PM
It is not the variable valve timing but the knock sensor that allows the ignition to be advanced some, with "super" fuels.

For many years I was firmly in the camp that believe if the octane is high enough to prevent knocking there is no benefit for higher octane. But the advent of knock detection and automatic ignition advance to the point where it is just not knocking, gives a technical basis why higher octane might be more efficient, or more powerful.

However I have never seen any convincing data supporting this. There are lots of reports by people who know which fuel they are using and therefore tend believe they notice a difference. I have used Shell 99 sobymetimes and don't believe I could tell which fuel was in the tank by power or economy.

I did  'blind trial' on my wifes Jazz a few years ago, she normally used super market fuel due to money off vouchers, I filled her Jazz up with 97 and she later asked me if I had tuned her care, as it felt smoother to drive and more perky. Now she didn't know she had better fuel in tank.
Title: Re: MPG for those interested.
Post by: culzean on August 02, 2019, 12:31:24 PM
From what I could tell the ethanol content was the same in each grade. I'll double check.

The higher octane fuels  used to be ethanol free, but ethanol can be used as a cheap and nasty octane booster. Ethanol is supposed to reduce CO2, which it does, but at expense of higher nox...
Title: Re: MPG for those interested.
Post by: mikebore on August 02, 2019, 12:39:29 PM
It is not the variable valve timing but the knock sensor that allows the ignition to be advanced some, with "super" fuels.

For many years I was firmly in the camp that believe if the octane is high enough to prevent knocking there is no benefit for higher octane. But the advent of knock detection and automatic ignition advance to the point where it is just not knocking, gives a technical basis why higher octane might be more efficient, or more powerful.

However I have never seen any convincing data supporting this. There are lots of reports by people who know which fuel they are using and therefore tend believe they notice a difference. I have used Shell 99 sobymetimes and don't believe I could tell which fuel was in the tank by power or economy.

I did  'blind trial' on my wifes Jazz a few years ago, she normally used super market fuel due to money off vouchers, I filled her Jazz up with 97 and she later asked me if I had tuned her care, as it felt smoother to drive and more perky. Now she didn't know she had better fuel in tank.

Thanks, that's a start!...did you try the other way round or any repeats to see if she could consistently tell?

Some tank-to-tank measurements over a decent period would be good. I use Fuelly but I haven't been very disciplined about recording fuel type or sticking to one type for a reasonable period. The problem is, as you or someone said, you can have the potential benefit as economy or performance. If more performance is available you have to drive without using it to measure the economy.
Title: Re: MPG for those interested.
Post by: culzean on August 02, 2019, 01:01:09 PM
https://en.wikipedia.org/wiki/Tetraethyllead

The availability of 100 octane fuel from the USA during WW2 played an important part in making Allied aero engines more powerful - it enabled them to use higher compression ratios and boost pressures which gave us an edge over our enemies.  The Germans were making most of their fuel and oils from Coal ( where the term 'synthetic oil ' came from, as it was synthesized from coal).   Germany did not have any sources of Oil and relied on a 'lightning war' to finish it before they ran out of reserves and production capacity from their synthetic plants, the longer the war went on the more likely they were to 'run out of gas' and lose.   The reason they were interested in North Africa and Southern Russia was the access to oilfields.
Title: Re: MPG for those interested.
Post by: zzaj on August 02, 2019, 01:35:57 PM
From what I could tell the ethanol content was the same in each grade. I'll double check.

"Esso super unleaded petrol (Synergy Supreme+ Unleaded 97) is ethanol free (except in Devon, Cornwall, the Teesside area and Scotland). They therefore advise anyone who has concerns about the presence of ethanol in petrol to use Synergy Supreme+ – providing they do not fill up in Devon or Cornwall, the Teesside area or Scotland." (Ex Esso website today).

Shell are more ambivalent. May be, may be not, sometimes yes, sometimes no! 

"In the UK, Shell regular unleaded and Shell V-Power unleaded are likely to contain some ethanol." (Ex Shell website today).

The others...........?
Title: Re: MPG for those interested.
Post by: zzaj on August 20, 2019, 05:24:17 PM
From what I could tell the ethanol content was the same in each grade. I'll double check.

"Esso super unleaded petrol (Synergy Supreme+ Unleaded 97) is ethanol free (except in Devon, Cornwall, the Teesside area and Scotland). They therefore advise anyone who has concerns about the presence of ethanol in petrol to use Synergy Supreme+ – providing they do not fill up in Devon or Cornwall, the Teesside area or Scotland." (Ex Esso website today).

Shell are more ambivalent. May be, may be not, sometimes yes, sometimes no! 

"In the UK, Shell regular unleaded and Shell V-Power unleaded are likely to contain some ethanol." (Ex Shell website today).

The others...........?

PS

My local Shell petrol station shows E5 (5% ethanol) on each of the 95RON and the 99RON (V Power) pumps.
Title: Re: MPG for those interested.
Post by: Downsizer on August 25, 2019, 04:56:47 PM
Warm weather certainly seems to be good for fuel economy.  In the last 7 days I have driven 922 miles from Suffolk to the Sussex coast and back, and then via York to North Shields and back, with local motoring at each stop.  I bought a total of 71 litres of ASDA 95 giving a real consumption of 59 mpg.  The display shows 63.8 mpg and average speed of 42 mph.  I used cruise control as much as possible - with CVT it seems to have much better accelerator control than I have!
Title: Re: MPG for those interested.
Post by: peteo48 on September 16, 2019, 10:19:26 PM
Last week, up in Scotland, I recorded my best ever tank on any of the 3 Jazzes I have owned. 57.4 mpg actual. This included the journey up to Motherwell where we overnighted so we could visit my wife's sister, then a trip to Ardrossan for the ferry to Arran. 325 miles all told mostly on good roads and motorways but some rush hour stuff in the Glasgow area (exacerbated by the sat nav lady giving me duff gen and getting me lost by advising me to keep left at one point on the M8 and causing me to exit the road when I should have stayed on it.
Title: Re: MPG for those interested.
Post by: Jocko on September 17, 2019, 08:26:05 AM
Great figures. I find rush hour traffic not as debilitating as you might think.
Title: Re: MPG for those interested.
Post by: peteo48 on September 26, 2019, 11:05:14 AM
Just got another 50 plus figure. Dead on 55 actual - this showed as 58.9 on the computer.

My last 10 fuel ups are now averaging 51 mpg. This goes back to the beginning of 2019 so includes some winter motoring. The next 10 won't be as good of course but, as I've got used to the CVT I think I've refined my driving style. Overall I'm pretty pleased.
Title: Re: MPG for those interested.
Post by: Jocko on September 26, 2019, 03:36:28 PM
Good numbers. Had a look at your Fuelly page and you can see how the time of the years impacts your mpg.
Title: Re: MPG for those interested.
Post by: mikebore on September 26, 2019, 04:26:09 PM
Good numbers. Had a look at your Fuelly page and you can see how the time of the years impacts your mpg.

Not much seasonal variation about mine over 40 months and 47,000 miles. Maybe a slight improvement during the period, which is how it feels subjectively.
Title: Re: MPG for those interested.
Post by: peteo48 on September 26, 2019, 05:06:43 PM
Good numbers. Had a look at your Fuelly page and you can see how the time of the years impacts your mpg.

Definitely because so much of my stop start stuff is compounded by low temps and, in the winter, it's rare to do much longer distance stuff. One thing I have noticed is that a 3 mile return trip to the supermarket is worse. much worse, than a 6 mile return trip to pick up our grandson as and when required even though the traffic conditions are pretty much identical. Obviously there would be a difference but it's a big one.
Title: Re: MPG for those interested.
Post by: Jocko on September 26, 2019, 05:36:43 PM
Yes, since my wife has been off work and my mother-in-law has required regular visits, the bulk of my trips have been 30+ miles. That makes a huge difference.
Title: Re: MPG for those interested.
Post by: Jadze on November 24, 2019, 02:59:40 PM
Hi,

Im new here. I just bought Jazz 2016 cvt 16K odo. Driving mostly ( lets say 75%) in the city, on W. Yorkshire hills, a bit motorway. No matter how hard I try and slow accelerate and etc, my average mpg is only 34 mpg. https://drive.google.com/open?id=1OxIpVLHX1BNQMQhlSz5Sg8gxeYEwB0-e
Just wonder what's wrong with my car...  ::)
Title: Re: MPG for those interested.
Post by: Jocko on November 24, 2019, 05:13:02 PM
Check your tyre pressures when cold.
Title: Re: MPG for those interested.
Post by: Jadze on November 24, 2019, 07:46:16 PM
Check your tyre pressures when cold.
Thanks.
Just checked, my 185/55 R16 its 31.5 PSI front  and around 30 PSI rear ones. It must be 33 PSI isn't?
Title: Re: MPG for those interested.
Post by: Jocko on November 24, 2019, 08:07:20 PM
I set mine, Mk 1, to 35 all round.
Title: Re: MPG for those interested.
Post by: Jadze on November 24, 2019, 09:28:57 PM
I set mine, Mk 1, to 35 all round.
wow  :o
Title: Re: MPG for those interested.
Post by: peteo48 on November 25, 2019, 10:38:58 AM
I set mine, Mk 1, to 35 all round.

There is a maximum pressure marked on all tyres and this will be well within that. I know that several EV drivers exceed recommended pressures to lower rolling resistance and increase range.
Title: Re: MPG for those interested.
Post by: Jocko on November 25, 2019, 11:01:28 AM
I set mine, Mk 1, to 35 all round.
wow  :o
A couple of psi over is better than a couple under. And I don't have to worry about them going under if I miss a pressure check (about once a month, weather permitting).
Title: Re: MPG for those interested.
Post by: culzean on November 25, 2019, 11:25:28 AM
Check your tyre wear pattern,  under-inflation can cause extra wear at edges of tread, and over-inflation causes more wear in centre of tread. 
Title: Re: MPG for those interested.
Post by: Jocko on November 25, 2019, 11:36:45 AM
Check your tyre wear pattern,  under-inflation can cause extra wear at edges of tread, and over-inflation causes more wear in centre of tread.
After 15,000 miles on these tyres the tread is uniform, across the pisté.
Title: Re: MPG for those interested.
Post by: Jadze on December 01, 2019, 10:58:15 AM
Hey guys.
I want to share what I found out after couple week experimenting with my Jazz. First of all, fuel. Tried Shell V-Power and I feel significant better mpg and better acceleration. Second, same as everyone advised - pumped all 4 tyres to 34 psi, feel like 3%-5% better mpg.
But third thing is a bit disturbing... In my opinion, speed limiter is poorly programed in Jazz. Without speed limiter set up, car is amazing - very consistent reaction to pedal, smooth acceleration. But if I just set speed limiter manually or setting Intelligent Speed Limiter, things become different. Starting acceleration with limiter on is truly limited also, then, if you push pedal down, it reacts a kick car forward, causing like enormous fuel spray in motor and of course, lowering my mpg. In other words, I noticed poor mpg with limiter on, and smooth nice acceleration and nice high mpg with limiter off.
I want to say that these are just my observations and I can be wrong, but that's what I noticed.
 
Title: Re: MPG for those interested.
Post by: Jocko on December 01, 2019, 11:08:07 AM
Tried Shell V-Power and I feel significant better mpg and better acceleration.
I found the same, but when I crunched the numbers I found the cost per mile cheaper using 95 octane.

https://clubjazz.org/forum/index.php?topic=11304.msg76310#msg76310 (https://clubjazz.org/forum/index.php?topic=11304.msg76310#msg76310)

Reply #33 says it all.

I am currently back on 95 octane from my nearest convenient supermarket.
Title: Re: MPG for those interested.
Post by: Jadze on December 06, 2019, 01:27:28 PM
Another thing (I'm sure many mentioned that before): cold engine mpg. Just started drive short  distance after 2 days (average temp outside 6-10C) and get only 26 mpg after 7 miles trip to shop.
Heres video about cold engine mpg (it's in polish, but you will get the idea):
Title: Re: MPG for those interested.
Post by: Jocko on December 06, 2019, 03:21:11 PM
After a discussion on another forum, on Wednesday I set my ScanGauge up to display coolant temperature and set off on my fairly regular trip to the south of Edinburgh. According to the local weather station the ambient was 8°C and the coolant temperature when I came out of the garage was 10°C.  It took a mile or so for the blue light to go out (55°C) and another couple of miles on the temperature got up to 81°C. Once I was on the motorway that dropped back to 79°C (probably due to the higher speed and greater airflow through the radiator). Now, in the summer, it usually runs at 83°C and anywhere up to 93°C. On Wednesday, for the 40 mile trip, it never got above 81°C.
Returning an hour later it read 50°C when I started out and the same thing happened on the way home.
Shortly before reaching Kirkcaldy I switched the heater off, and then it climbed to 83°C, but only accelerating away from junctions, and while climbing a steep hill.
What this says to me is that in the winter, the engine never gets completely warmed up, and even that couple of degrees must effect fuel efficiency. So for the best fuel efficiency in winter, keep your speed down and if you can, leave your heater off (My wife always takes her coat off before getting in the car whereas I don't. I keep telling her that in an accident, if trapped in the car, she could die of hypothermia before she is cut out!).
Title: Re: MPG for those interested.
Post by: John Ratsey on December 06, 2019, 06:56:34 PM
Another thing (I'm sure many mentioned that before): cold engine mpg. Just started drive short  distance after 2 days (average temp outside 6-10C) and get only 26 mpg after 7 miles trip to shop.
This is one of my complaints. I think Honda could have done more to help the engine warm up quickly but when fuel efficiency is tested using pre-warmed engines there was no incentive to address this aspect. Now the fuel economy tests include some "real life" conditions the vehicle manufacturers have started to do something. The current CR-V has moveable louvres (or similar) on the air intake for the engine compartment - the modern equivalent of drivers blocking off half the radiator in a previous era (when it was more accessible). I hope that the Mk 4 Jazz has a similar feature, maybe more.

My current work-around is to turn off the cabin heating for the first few minutes of a cold start journey to give the engine some help in getting warm.
Title: Re: MPG for those interested.
Post by: Jocko on December 06, 2019, 10:01:55 PM
My current work-around is to turn off the cabin heating for the first few minutes of a cold start journey to give the engine some help in getting warm.
I never turn the heater on until the blue light goes out, and when it is below zero, I leave it a couple of minutes after that. In really low temps the blue light has gone out, I have immediately turned the heating on, and the light has come back on. Especially at high fan settings.
Title: Re: MPG for those interested.
Post by: Kenneve on December 06, 2019, 10:52:05 PM
If you set the heating to Auto, in my EX, the fan won't start until the blue light has gone out, which in effect is the same as what Jocko says. Obviously Honda have done this to ensure that the engine warms up quickly.
Title: Re: MPG for those interested.
Post by: peteo48 on February 21, 2020, 01:26:21 PM
Little quirk or possibly not on my new Jazz. All the Jazzes I've had to date exaggerate mpg by about 10% on the computer - this is usually about 4 mpg give or take.

Done 2 fuel ups on the new car. The first was 39.3 actual, 41.2 computer. Today's fuel up is 49.6 actual but 51.8 on the computer.

Never had the computer come this close to the actual figures before. 2 fuel ups is not a lot but I'm wondering if any tweaks have made the computer more accurate or do the 16 inch wheels make a difference? I guess a true pattern might emerge after a few more tanks.
Title: Re: MPG for those interested.
Post by: Jocko on February 21, 2020, 04:33:04 PM
That's about the error I see on my Mk 1. Last top up was 54.3 for an actual 52.1.
Title: Re: MPG for those interested.
Post by: langserve on April 18, 2020, 03:26:06 PM
I have almost 10 months of data and the error is about 10% for my new GK3. On my much missed GD1 it was 11%. I rather suspect Honda know exactly what they are doing and are deliberately overstating by 10% in the interests of consumer satisfaction. How many people actually check I wonder?

Incidentally my averaged economy for the GD1 was 31 mpg and for the GK3 it is 38.4 mpg. I've been doing a fair bit more long distance driving recently but the GK3 is clearly outperforming. You folks are clearly doing a lot better than me which I think is because of a lot of very short distance stuff and the fact the aircon has to work so hard in the summer. Perhaps I am a bit heavy footed as well.
Title: Re: MPG for those interested.
Post by: peteo48 on April 18, 2020, 04:01:45 PM
With the lockdown I'm doing very few miles - about 60 in total since early March and these are odd trips for shopping etc. I'm showing 38.8 on the car's computer but it's probably about 35 in real terms.