Author Topic: MPG for those interested.  (Read 61706 times)

peteo48

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Re: MPG for those interested.
« Reply #330 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?

culzean

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Re: MPG for those interested.
« Reply #331 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.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

peteo48

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Re: MPG for those interested.
« Reply #332 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.

culzean

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Re: MPG for those interested.
« Reply #333 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.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

culzean

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Re: MPG for those interested.
« Reply #334 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...
« Last Edit: August 02, 2019, 12:46:39 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

mikebore

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Re: MPG for those interested.
« Reply #335 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.

culzean

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Re: MPG for those interested.
« Reply #336 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.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

zzaj

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Re: MPG for those interested.
« Reply #337 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...........?

zzaj

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Re: MPG for those interested.
« Reply #338 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.

Downsizer

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Re: MPG for those interested.
« Reply #339 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!
« Last Edit: August 25, 2019, 04:58:37 PM by Downsizer »

peteo48

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Re: MPG for those interested.
« Reply #340 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.

Jocko

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Re: MPG for those interested.
« Reply #341 on: September 17, 2019, 08:26:05 AM »
Great figures. I find rush hour traffic not as debilitating as you might think.

peteo48

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Re: MPG for those interested.
« Reply #342 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.

Jocko

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Re: MPG for those interested.
« Reply #343 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.

mikebore

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Re: MPG for those interested.
« Reply #344 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.

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