E10 petrol mpg, anyone noticed a difference?
E10 petrol mpg, anyone noticed a difference?
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Discussion

willmagrath

Original Poster:

1,387 posts

176 months

Sunday 26th December 2021
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As it says, i think ive noticed a difference, and the press is full of the usual daily express style horror stories.

Anyone noticed worse mpg with the standard new E10 petrol?

ChocolateFrog

34,954 posts

203 months

Sunday 26th December 2021
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Well it will be worse, that's just a fact.

kambites

71,563 posts

251 months

Sunday 26th December 2021
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ChocolateFrog said:
Well it will be worse, that's just a fact.
Yes but it shouldn't really be noticeably worse. The energy density of E10 is, what, 1% lower than that of E5? So if your car does 30mpg on E5 it should do 29.7mpg on E10 if it's burning it as efficiently. Unfortunately it seems that some cars don't burn it anywhere near as efficiently.

pits

6,704 posts

220 months

Sunday 26th December 2021
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My E46 330ci has dropped from 34mpg down to 28mpg and definitely feels lethargic, but I haven't run it on E5 for ages, but the only available now is super which should run better anyway. but I have noticed it, as has my brother in his C70 that has dropped as well.

V8covin

10,220 posts

223 months

Sunday 26th December 2021
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pits said:
My E46 330ci has dropped from 34mpg down to 28mpg and definitely feels lethargic, but I haven't run it on E5 for ages, but the only available now is super which should run better anyway. but I have noticed it, as has my brother in his C70 that has dropped as well.
I've gone the other way and only use super unleaded now and have noticed a slight increase in economy

hedges88

690 posts

175 months

Sunday 26th December 2021
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pits said:
My E46 330ci has dropped from 34mpg down to 28mpg and definitely feels lethargic, but I haven't run it on E5 for ages, but the only available now is super which should run better anyway. but I have noticed it, as has my brother in his C70 that has dropped as well.
Not much of a suprise. Using 95 octane in a situation where you can't get 97+ is acceptable on occasion but a BMW M54 REQUIRES high octane fuel to operate properly. Otherwise what's the point in Double VANOS, a variable inlet manifold and all the other technology that engine has. I had an M54 in my E39 and it ran like crap on 95RON and that was long before 10% ethanol. No point in running around with retarded timing all the time....

ric p

715 posts

299 months

Sunday 26th December 2021
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Not completely test conditions but I do the same A road and dual carriageway 35 miles to work outside of rush hour with very little other mileage in myVolvo c30 T5, so not really designed to hypermile.. And try to use cruise as much as possible so the journeys are pretty identical. All fuel comes from my local Ilminster Shell garage.

On E5 95 I managed a pretty steady 34.4 over the year. E10 95 seemed to drop it back to 33.8, which would sort of make sense. So I’m now doing a V-Power trial (A bit nerdy and SWMBO rolls her eyes) and currently getting 35.8 but need a few more tank fulls to average that figure out.

Whether it is worth the premium is another question. However certainly the E10 bit appears to be a backwards step for engine efficiency. Greta would be disappointed.

CrgT16

2,527 posts

138 months

Sunday 26th December 2021
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Osso ou completely psychological but after 4 tanks of E10 I went back to VPower E5. On E10 I had worse mpg and the car sounded harsher.

It can run both but for me feels better on the E5 VPower which I used to run before. Could be just the additives of BPower compared to the more regular fuel and nothing to do with the thank content.

anonymous-user

84 months

Sunday 26th December 2021
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kambites said:
Yes but it shouldn't really be noticeably worse. The energy density of E10 is, what, 1% lower than that of E5? So if your car does 30mpg on E5 it should do 29.7mpg on E10 if it's burning it as efficiently. Unfortunately it seems that some cars don't burn it anywhere near as efficiently.
Ethanol at 5% in petrol requires 2% more fuel injected to hit target AFR than pure petrol. Ethanol at 10% in petrol requires 4% more fuel injected than pure petrol.

So going from worst case E5 to worse case E10 should see a 2% drop in MPG, assuming everything else stays equal.

The reality will depend on how active your ECU is and the base mapping, a good ECU will advance the ignition to compensate for the slower burn rate of the ethanol, if it isn't good enough to do that, then the efficiency of the engine will drop, so you are likely to burn more fuel for the same torque output.

anonymous-user

84 months

Sunday 26th December 2021
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My car had started sounding harsher on E10. It just doesn’t sound well. Haven’t noticed an MPG drop though.

pits

6,704 posts

220 months

Monday 27th December 2021
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hedges88 said:
pits said:
My E46 330ci has dropped from 34mpg down to 28mpg and definitely feels lethargic, but I haven't run it on E5 for ages, but the only available now is super which should run better anyway. but I have noticed it, as has my brother in his C70 that has dropped as well.
Not much of a suprise. Using 95 octane in a situation where you can't get 97+ is acceptable on occasion but a BMW M54 REQUIRES high octane fuel to operate properly. Otherwise what's the point in Double VANOS, a variable inlet manifold and all the other technology that engine has. I had an M54 in my E39 and it ran like crap on 95RON and that was long before 10% ethanol. No point in running around with retarded timing all the time....
I have put 110k miles on the car, always on 95 ron, on a run it does 40+mpg around town it has always averaged 33-36mpg, it is still as quick as it has ever been at 205k miles, my previous 4 E39's ran fine on it as well, get the quoted figures for mpg out of them, higher ethanol content, now it is lethargic and mpg has dropped.
Vanos doesn't work, it has done 205k miles, it's an M54 you should be surprised it even has oil in it,

Attics Finch

29,033 posts

213 months

Monday 27th December 2021
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Elderly merc with M104 engine.


I've been using both for yrs, Europe and UK. I've not noticed any difference.

hedges88

690 posts

175 months

Tuesday 28th December 2021
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pits said:
I have put 110k miles on the car, always on 95 ron, on a run it does 40+mpg around town it has always averaged 33-36mpg, it is still as quick as it has ever been at 205k miles, my previous 4 E39's ran fine on it as well, get the quoted figures for mpg out of them, higher ethanol content, now it is lethargic and mpg has dropped.
Vanos doesn't work, it has done 205k miles, it's an M54 you should be surprised it even has oil in it,
M54s use oil like a rotarylaugh And yes VANOS seals etc do go wrong. Doesn't change the fact that if you use high octane fuel the engine can work at it's best. Long term use of 95 octane means that the engine isn't running optimally which then has knock on effects

Mr Tidy

31,605 posts

157 months

Tuesday 28th December 2021
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Both of my BMWs recommend at least 98 RON whenever possible, so neither has had to suffer E10 yet as my nearest filling station has Tesco Momentum 99 RON!

hedges88

690 posts

175 months

Tuesday 28th December 2021
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Mr Tidy said:
Both of my BMWs recommend at least 98 RON whenever possible, so neither has had to suffer E10 yet as my nearest filling station has Tesco Momentum 99 RON!
Well done for following the instructions.

All of these stupid Daily Express articles about how E10 has ruined their car etc, the majority are VAG group car owners with FSI engines that should have been running premium the whole time anyway rolleyes

mcflurry

9,190 posts

283 months

Tuesday 28th December 2021
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Made no real difference to me - mid 40s with "old" petrol and low 40s with the new stuff.
The price going up 90p a gallon in the last couple of months has way more impact..

Milkyway

14,660 posts

83 months

Tuesday 28th December 2021
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My Dad has a ‘05 Astra, & he noticed the difference from day one, especially when he’s towing his caravan.
As he puts it... “It’s got no guts in it”.
Yet his brother hasn’t noticed any difference in his Suzuki... but he always has to have the opposite answer.
( So... probably it has affected him too)

( NB: How long before we are putting something ‘extra’ in the tank)

Edited by Milkyway on Tuesday 28th December 18:05

Chris32345

2,141 posts

92 months

Tuesday 28th December 2021
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hedges88 said:
Not much of a suprise. Using 95 octane in a situation where you can't get 97+ is acceptable on occasion but a BMW M54 REQUIRES high octane fuel to operate properly. Otherwise what's the point in Double VANOS, a variable inlet manifold and all the other technology that engine has. I had an M54 in my E39 and it ran like crap on 95RON and that was long before 10% ethanol. No point in running around with retarded timing all the time....
what's the poi6 in a road engi6 that doesn't run on normal fuel

Milkyway

14,660 posts

83 months

Tuesday 28th December 2021
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I heard a rumour that Volkswagen are going to produce their own special fuel. scratchchin

Edited by Milkyway on Tuesday 28th December 18:06

ahenners

621 posts

156 months

Tuesday 28th December 2021
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Yeah it seems worse, at a guess somewhere around 5-7%