I have a four-year old Kia Niro. I have only done just over 11,000 miles to date. This is partly owing to trying to walk amuch as possible and one of the results of the pandemic.
However, up to two years when I could actually do more than just locval trips I got the consumption on average up to 73mpg.
Until my last tank top up it had gone down to 63mph. Since then it is down to under 53mph. I cannot swear that it is the change to E10 but .....
I switched my car to higher octane stuff - I can't find out whether or not it's E10 compatible.
MPG has improved noticeably. More than 10%. Should have done it years ago!
Andy
My change in mileage over the last three years is less than yours, but still clear (63 > 58 mpg). But it's a diesel, so no E10 or similar involved, AFAIK. I put it down to shorter mileage trips with the engine not warming up fully, and less use, due to Covid.
I had the opposite experience with two long round trips of 550 miles, one E5 and one E10. The E10 trip gave a little better mileage and traffic conditions seemed the same.
However, these trips were both there for a few days then back, and looking at the weather it was headwind both ways on E5, relatively calm on E10.
It is. There is simply less energy in alcohol than in straight hydrocarbon. Ethanol is 27MJ/kg: Gasoline is 46MJ/kg
Specific gravity is similar.
Naturally tax is on a per litre basis so E10 is taxed more than ordinary gasoline in terms of energy content. Nice trick huh?
Ratio of energy should be something like (0.9 * 47 +0.1* 27)/47
around 95% However there is no guarantee that efficiencies are the same.
If your figures are accurate then you are burning more fuel and emitting more CO2 when using E10.
a quick google (I run on diesel: I don't habitually know petrol prices) suggests that E5 is about 10% more expensive than E10: If your figures are accurate, then you would be paying less to fill up with premium petrol and get your mileage back.
Yes. If I brake a lot on short trips my MPG is below 30, on longer trips its better than 35.
V6 twin turbo 3 litre diesel.
And, depending on where you live/buy fuel, the E5 fuel can actually be E0, so more of a difference to start with.
I've recently done 400 miles of motorway driving and my fall is around
5% using E10 compared to that for similar previous journeys. Obviously on a sample of one long trip my results are hardly statistically valid.
how come ethanol has more energy then ? ...
Could be some problem with the engine or the management system though. It might be there is a tweak that can be done to get it better. Brian
oh right
Shorter carbon chains (ethanol is C2H5OH - just two carbons - compared with octane and its derivatives which have 8 carbons, and other similar alkanes and alcohols).
Esso 99+ petrol does not have ethanol in the South East according to their website :-.
"Although our pumps have E5 labels on them, our Synergy Supreme+ 99 is actually ethanol free (except, due to technical supply reasons, in Devon, Cornwall, North Wales, North England and Scotland). Legislation requires us to place these E5 labels on pumps that dispense unleaded petrol with ?up to 5% ethanol?, including those that contain no ethanol, which is why we display them on our Synergy Supreme+ 99 pumps.
There?s currently no requirement for renewable fuel, like ethanol, to be present in super unleaded petrol although this could change in the future, in which case we would comply with any new legislation."
And esso supply tesco, who sell 99 octane fuel, which (except in the areas noted) will be E0 labelled as E5
That is an interesting calculation, I had not realised that.
Perhaps a better way to look at it is that petroleum just has carbon and hydrogen atoms, both of which release energy when oxidised. The alcohol is carrying the dead weight of 16/46 or 35% of its mass as oxygen (which doesn't burn).
(The same argument applies to the Fatty Acid Methyl Esters in biodiesel).
The net calorific value of petrol is about 43 MJ/kg, for ethanol it is about 20 MJ/kg.
How long before the 99 octane tax goes up, I wonder.
Miles per gallon versus mpm -- miles per money:-)
Thomas Prufer
Odd. My last three cars recommend the high octane stuff where you can get it. But obviously can run on standard 95 too. I do one long journey quite regularly - about 500 mile each way. And do one journey on 95. The other on 97/8. Quite a ritual. But have never had a definitive difference in MPG. And not a noticeable difference in performance either.
Is it true that filling stations in Germany sell 102 octane petrol ?
Yes, some do -- "Aral Ultimate 102".
Thomas Prufer
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.