Author Topic: What MPG are you getting from your Mk1 Honda Jazz ?  (Read 201497 times)

John Ratsey

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #345 on: March 25, 2019, 11:09:21 AM »
I know mine's a Mk3 but this is the most interesting thread for mpg matters!

Ideally, I need to be getting back to the no higher than 2,500 rpm idea before changing up (or the CVT selecting a higher ratio).
I agree about this interesting discussion.

The challenge with the Mk 3 Jazz, particularly the CVT version, is keeping it in the more efficient Atkinson cycle mode. I found that there was a gap in the performance characteristics and it was difficult to achieve smooth acceleration (I recall that the sales info at the time claimed this to give a more sporty feel): Either be very easy on the right foot and accelerate slowly or push a bit harder and be quickly breaking the urban speed limits. Hence after a year my Mk 3 was traded in for a CVT HR-V. The latter doesn't have the Atkinson cycle mode and has a better relationship between pushing pedal and performance. So far, the HR-V has averaged 50.4 mpg compared to 57.8 mpg I achieved during a year with the Mk 3 Jazz - only 13% difference for similar driving style and conditions.

I thought I had read somewhere that the Mk 3 Jazz refresh has some tweaked settings for the CVT behaviour which might be to address this performance gap, but can't now find anything.
2022 HR-V Elegance, previously 2020 Jazz Crosstar

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #346 on: March 25, 2019, 11:25:30 AM »
Part of that might be attempting to by pass the initial sluggishness by flooring the gas pedal and finding the revs going up to nearly 4,000 rpm on occasions
Try switching your dashboard display to instantaneous mpg. That is my guide. Opening the throttle wide is not a bad ploy, but flooring it is not a good idea. About 80% is a reasonable amount. You want to keep the ECU in closed loop control. Too much throttle gets you into open loop, and that is a bit like the old accelerator pump on a downdraught carb.

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #347 on: March 25, 2019, 08:00:01 PM »
Checked my tyre pressures and they are spot on. Since seeing how good my mpg figure was I found my coasting a lot "freer", a bit like how the car always feels smoother on the way back with a fresh MOT than it does on the way to the testing station.

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #348 on: March 26, 2019, 11:42:23 AM »
Today I came home from Edinburgh and came along my usual route from the A909, via the B925 to the A910. 6.0 miles, junction to junction. I reset my Current trip as I started, but had a disappointing journey spoilt by a lorry reversing into a property and a man with a STOP/GO board for white lining. My ScanGauge E still recorded 92.1 mpg for the 6 mile trip. Pleased with that.

Kiwikea

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #349 on: April 01, 2019, 02:32:29 PM »
Hi I have a 2007 jazz sport 1.5 cvt7, I get 46-50 mpg  for the hills I drive over in New Zealand

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #350 on: April 01, 2019, 04:46:15 PM »
Welcome. We didn't get a 1.5 Jazz until the 2019 model Sport. 46 - 50 is good mpg for the larger engine.

TheFlyingPostman

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #351 on: April 03, 2019, 04:14:45 PM »
I have K&N performance filter, NGK IRIDIUM spark plugs and EGR blank I have see massive improve in performance with lightness on right pedal 3 mpg more than pervious 53mpg. Very pleased with it.

Got this from https://www.ebay.co.uk/itm/8x-NGK-IRIDIUM-IX-UPGRADE-Spark-Plugs-HONDA-JAZZ-1-4-i-DSI-TWIN-SPARK-02-3764/360475871112
« Last Edit: April 03, 2019, 04:18:50 PM by TheFlyingPostman »

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #352 on: April 20, 2019, 05:34:46 PM »
Nice warm day today (too warm as I have no air con!). Easter traffic was really busy. The combination of these factors meant I managed 58.9 mpg (ScanGauge E) for my usual 80 mile, Saturday, round trip.

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #353 on: April 22, 2019, 07:11:48 AM »
Filled up with petrol today. It was just a top up, as I had a Morrisons 5p/litre off voucher, and the promotion ends today. Calculated figure was 57.1 mpg which, surprisingly, was the dash read out as well!
Petrol was cheaper to buy, when I got the voucher, than it was this morning with the 5p off !!!!
And it is to get dearer. The US has just announced hardening sanctions against Iranian oil, which has already pushed up Brent crude.

smilertoo

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #354 on: April 22, 2019, 10:37:15 AM »
long motorway run yesterday pushed my mpg from 38 to 45.

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #355 on: April 22, 2019, 12:22:31 PM »
long motorway run yesterday pushed my mpg from 38 to 45.
I find my best mpg figures on the motorway are around 60 mph on the speedo, 53 mpg on the GPS.

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #356 on: April 29, 2019, 06:56:46 AM »
Got a respectable figure for my mpg this tankful. 57.7 mpg calculated (Fuelly.com). This week I have done a lot of longer runs (80 miles), albeit many into Edinburgh city centre, and almost no daily commutes. The warmer weather makes a difference too.

springswood

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #357 on: April 30, 2019, 09:07:04 AM »
That's more than respectable, Jocko, it brilliant. I'm still not getting anywhere near. I'm definitely becoming very curious what I can do to improve mpg. I do all I can with driving style. I've now done a full service with standard parts but that's only got me a couple of mpg (I have no fixed driving pattern so it's not easy to compare).

I tried an EGR plate but it didn't make much difference to running or economy. So I suspect, Flying Postman, it may be down to the iridium plugs. They don't just last longer, they give a better spark. The physics is that smaller electrodes give higher electrostatic shear forces that ionises the air more effectively. It's the same reason lighting conductors are sharp. The air filter probably helps. Do you have the cone one or the one that replaces the standard filter?

The latest in my search for the lost mpg is to try a catalytic converter cleaner. They say carbon deposits build up and my cat seems to be the original 10 year old one. I'm thinking that might mislead the oxygen sensors and cause the ECU to bung too much fuel in. I'll post when I've used a tankful and topped up. According to the dashboard display I'm doing 46 mpg which is 3 or 4 up on usual, though I have also had some longer runs.
"Indecision is a terrible thing"
Or is it? What do you think?

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #358 on: April 30, 2019, 10:17:08 AM »
I use standard plugs (not Iridium) and the eight plugs have been in for two years. I intend leaving them another year before I change them. Air filter is just bog standard from a local motor factor. It has been in two years and about 18K miles, so I may change it next service. Oil is just cheap 5w-30 synthetic.
Cat was replaced two years ago but I actually noticed a 10% drop in mpg immediately after replacing it.
I do set my cold tyre pressures to 35 psig and regularly feel my wheel centres after a trip (in case of any brake rubbing).
I tend to drive for economy, with little brisk acceleration, unless road conditions demand it. On a downhill stretch, if there is nothing behind me, I will let the car pick up speed by its self, rather than by accelerating (I am retired, and when I am in the car by myself I am seldom in a hurry). I seldom drive fast. I find that on the open road a GPS speed of around 53 mph (just under 60 on speedo) suits me and returns best numbers.
I do have my ScanGauge E fitted to binnacle and it displays my trip average and instantaneous mpg, and I constantly try to keep the latter higher than the former.


peteo48

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #359 on: April 30, 2019, 10:38:26 AM »
The cruising speed on the motorway is a biggie. There are stats available but the difference between 60 mph and 70 mph is significant. Found this out in 2017 on a trip down to Cornwall. A longish cruise, mostly at 70 or even a bit above, returned 49 actual in my 1.4 Mk 2.

My best return in that car was a tad over 56 mpg. This was achieved on the M56/M53 at a busy time when it was actually almost impossible to reach 70.

I used to aim for 75 on the speedo (reckoning that would be an actual 70). I now aim for dead on 70 (setting cruise to that if possible) and this shows as a "real" 66 mph on the sat nav. Quite a decent speed and a good compromise between speed and economy

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