Motoring Discussion > Ford - E5 vs E10 fuel Green Issues
Thread Author: legacylad Replies: 14

 Ford - E5 vs E10 fuel - legacylad
Not sure if this has been covered....
I don’t keep any record of my mpg save what might be the current mpg on my trip computer. A few friends have said that they get 10% less mpg running on E10 ( Golf GTE ) and I was curious if any high mileage drivers had noticed a difference over several thousand miles ?

With my low annual mileage ( I drive more miles in Spain than the U.K.) it doesn’t make a jot of difference....filled up an almost empty tank today with Tesco E5 Momentum @ £1.51 litre.

Normally I fill up with E10 stuff...almost the same price out in the sticks
 Ford - E5 vs E10 fuel - Zero
No difference here.
 Ford - E5 vs E10 fuel - Crankcase
Very vaguely, might be a bit less. I don't keep records so you just get a feel for what the computer reads for journeys. I've noticed a few times I expect a figure from experience but it's two or three less.

Could be other things like temperature or head winds though. Anyway, I'm getting 57 or 58 instead of 61 or 62, that kind of thing.
 Ford - E5 vs E10 fuel - Bromptonaut
>> No difference here.

I'd say that too. I use an App on my phone to record brim/brim refuellings for the Fabia. Nothing significant since E10 became a thing.

However, having lost my phone last week I've no longer got the pre E10 data.
 Ford - E5 vs E10 fuel - Manatee
We know ethanol is c. 30% less energy dense than gasoline so we will lose some mpg, all else equal.

Starting with 100% gasoline, you should expect to lose 1.5% MPG if you substituted a 95:5 gasoline/ethanol mix, or 3.0% if you went to 90:10.

E10 might not contain 10%, it must contain between 5% and 10%. Same with E5, mutatis mutandis.

E.g. it's reported that Esso Synergy Supreme (E5) has 0% ethanol in some regions.

The question is whether you can measure 3% difference or less, or if that is lost in the noise when you try to compare one tank with another.

That might be modified a bit if the engine is more or less better at achieving complete combustion on a different blend.
 Ford - E5 vs E10 fuel - Clk Sec
I'm now using E5, as my modest limousine is only used infrequently, and as far as I'm aware, E10 has a much reduced shelf life.

Half a tank of petrol lasts me several weeks.

 Ford - E5 vs E10 fuel - Zero
As mine achieves the same MPG even using higher octane fuels, I can assume then its throwing any gains in calorific value down the crapper?
Last edited by: Zero on Fri 4 Feb 22 at 10:57
 Ford - E5 vs E10 fuel - Manatee
Higher octane doesn't mean higher calorific value. It just means it has better anti-knock performance. If your car is clever enough, which it could well be, it can might use that to extract a bit more power by advancing the ignition a bit.

If anything the higher octane fuel might actually be less energy dense.
 Ford - E5 vs E10 fuel - Manatee
Does anybody remember Cleveland Discol? I certainly remember the name from my youth. That was an alcohol blend. The ethanol was made by Distillers group.
 Ford - E5 vs E10 fuel - Dog
I can only go by my car's computer - down from 43/44 smiles per galleon, to 39/40 on the same regular journeys at the same mimsing speed (Mrs Dog) since using ee ba gum 10.
 Ford - E5 vs E10 fuel - Mr Moo
I’m giving the lawnmower a diet of E5, on the basis that I want the thing to run in the spring and not need a gunk-filled tank draining. Seems ludicrous running a 20 year old mower on V-Power, but hey ho
 Ford - E5 vs E10 fuel - sooty123
I've noticed on the mpg readout on the dash, the mpg has dropped 2/3 mpg over similar journeys. I had wondered why it was down, I guess that's why.
 Ford - E5 vs E10 fuel - smokie
Maybe the colder weather?

Oh no, that's EVs :-)

(Though I guess cold will affect performance of ICE engines too...?)
 Ford - E5 vs E10 fuel - PeterS
>> Maybe the colder weather?
>> Oh no, that's EVs :-)
>> (Though I guess cold will affect performance of ICE engines too...?)

Certainly used to be the case with diesels, from an economy perspective, but not sure about turbo petrol engines. Don’t they perform better in lower temperatures, as the air is denser and has more oxygen per litre or something. Haven’t noticed any impact on economy, and the mild hybrid system in the Merc has the heater blowing warm air in 10 or 15 seconds, defrosting the screen quicker than the heated one in the MINI
 Ford - E5 vs E10 fuel - Manatee
They can make more power when it's cold simply because they are pumping denser air. The engine just adds more fuel. It probably doesn't affect the efficiency much when it's up to temperature, net, but it will extend the warm up period a bit.
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