Fuel Mileage with Ethanol Added?

[Merkava_4]

Your gasoline with ethanol added to it is not going to have as much energy content as
straight gasoline. You guys have any idea what the actual differences in mileage are?

 

[FordTrucks71]

Some say up to 25% from what ive been told..Google it!

 

[oilmutt]

Count on 30% less mpg.

 

[Shannow]

Count on those two answers being wrong...

If ethanol had zero calorific value, E10 should lose 10% of it's miles per pound.

But it doesn't...it's got 61% of the energy per pound, so E10 in theory will drop about 4% mileage per pound of fuel...

Take half the ethanol content as a probable mileage loss, unless you are playing high ethanol contents with engines that are optimised to use it

 

[SteveSRT8]

Originally Posted By: Merkava_4
Your gasoline with ethanol added to it is not going to have as much energy content as
straight gasoline. You guys have any idea what the actual differences in mileage are?


In our fleet of V8 powered pickups and vans the hit is a solid 10%.

 

[MaxZX]

2003 Mustang GT, 4.6L, 5 speed manual

When I got the car 2 years ago, I ran the first five tanks of gas using regular unleaded containing "up to 10%" ethanol. Average mpg was 21.2. Same station sells ethanol free gas, which I used for the next 5 fill-ups. Average for that was 22.8 mpg. Same driving habits, locations, patterns, etc. Mileage checked by hand calculating at each fill.

 

[JHZR2]

Originally Posted By: Shannow
Count on those two answers being wrong...

If ethanol had zero calorific value, E10 should lose 10% of it's miles per pound.

But it doesn't...it's got 61% of the energy per pound, so E10 in theory will drop about 4% mileage per pound of fuel...

Take half the ethanol content as a probable mileage loss, unless you are playing high ethanol contents with engines that are optimised to use it



Excellent, a real answer based upon the actual chemistry of the situation.


User error is the far greater effect on MPGs... As well as traffic and untamed stop lights.

 

[Finz]

Originally Posted By: Shannow
Count on those two answers being wrong...

If ethanol had zero calorific value, E10 should lose 10% of it's miles per pound.

But it doesn't...it's got 61% of the energy per pound, so E10 in theory will drop about 4% mileage per pound of fuel...

Take half the ethanol content as a probable mileage loss, unless you are playing high ethanol contents with engines that are optimised to use it



Shannow... would you run this by my again please? I don't follow - are you saying:

E10 addition to fuel sacrifices 4% per pound? So a 30 mpg car would lose 24% mpg based on a 6 pound gallon of E10 fuel and run at 23 mpg?

 

[Rolla07]

Originally Posted By: JHZR2
Originally Posted By: Shannow
Count on those two answers being wrong...

If ethanol had zero calorific value, E10 should lose 10% of it's miles per pound.

But it doesn't...it's got 61% of the energy per pound, so E10 in theory will drop about 4% mileage per pound of fuel...

Take half the ethanol content as a probable mileage loss, unless you are playing high ethanol contents with engines that are optimised to use it



Excellent, a real answer based upon the actual chemistry of the situation.


User error is the far greater effect on MPGs... As well as traffic and untamed stop lights.


Agreed. How would a fuel with 10% ethanol result in 30% loss of mpg? Makes no sense. I have used both and the difference in mpg is neglible. Not to say I like ethanol in our gas.

 

[lubedude13]

My car before ethanol got 32-34 all day. Same trip now I get 29-30.5
My camry got 30mpg going on a 3 hr trip last year. The same trip this year with pure gas got 36mpg. Now I know there could be a small difference in how I drove etc but not 6 mpg

 

[racer12306]

Originally Posted By: Finz
Originally Posted By: Shannow
Count on those two answers being wrong...

If ethanol had zero calorific value, E10 should lose 10% of it's miles per pound.

But it doesn't...it's got 61% of the energy per pound, so E10 in theory will drop about 4% mileage per pound of fuel...

Take half the ethanol content as a probable mileage loss, unless you are playing high ethanol contents with engines that are optimised to use it



Shannow... would you run this by my again please? I don't follow - are you saying:

E10 addition to fuel sacrifices 4% per pound? So a 30 mpg car would lose 24% mpg based on a 6 pound gallon of E10 fuel and run at 23 mpg?



No, what he is saying is...


100% gasoline = 100% energy
100% ethanol = 61% energy compared to gasoline

Therefore, when using E10, you are using 90% gasoline at 100% and 10% ethanol at 61% energy. Which leads you to an approximate of 4% loss in fuel economy.


Note: I did not check the math, but it looks plausible.


I'm curious to see how this works out because I'm actually going to have a full tank of commuting on my Neon for the first time in 5.5 years so I haven't seen a real world fuel economy in a while.

 

[Eddie]

I calculated the actual value at minus 4.3% loss. Ed

 

[SwampSurvivor]

10-20% on Jeep 4.0s.

 

[FZ1]

Cost me 15% mpg in my Accord V6.

 

[AandPDan]

I lose 10% in my 4.7 Dakota.

 

[Garak]

Originally Posted By: Shannow
Count on those two answers being wrong...

Agreed. When I had the old Audi, I could consistently get more miles out of a tank of pure premium versus ethanol enhanced premium. That's the only way I could really tell. Calculating fuel economy obviously has its pitfalls if you want to compare numbers. Fortunately, the old Audi had a very large tank, and the extra miles were noticeable. But, it was nowhere near 10%, let alone significantly higher than that. I got about 6 or 7% more miles per tank of pure gas, and I'd consider that optimistic rather than conservative.

 

[Kestas]

My calculations show a theoretical 4.4% loss of available energy with E10. When I tracked gas mileage long time ago, flip-flopping between E10 and pure gas, my calculated mpg loss with E10 came close to theoretical.

 

[Shannow]

Originally Posted By: Finz
Originally Posted By: Shannow
Count on those two answers being wrong...

If ethanol had zero calorific value, E10 should lose 10% of it's miles per pound.

But it doesn't...it's got 61% of the energy per pound, so E10 in theory will drop about 4% mileage per pound of fuel...

Take half the ethanol content as a probable mileage loss, unless you are playing high ethanol contents with engines that are optimised to use it



Shannow... would you run this by my again please? I don't follow - are you saying:

E10 addition to fuel sacrifices 4% per pound? So a 30 mpg car would lose 24% mpg based on a 6 pound gallon of E10 fuel and run at 23 mpg?


Sorry, I switched to energy content per Kilogramme, which is my native tongue, changed it to a percentage, then used it per pound of "ingredient" in the fuel brew.

e.g.
Petrol has 44MJ/Kg (think BTU per pound), Ethanol has 26.9 MJ/Kg...therefore a KG of ethanol has 61% of the energy of a KG of petrol, and same pound for pound.

So E10 has "90" (for the 90% petrol) plus "6.1" for the 10%x61% for the ethanol, and loses the about 4% number.

to turn it into volume, you need another conversion. Ethanol is pretty specific at an S.G. of 0.785 (grammes per CC, water SG = 1), while petrol has a range, 0.72 to 0.79 (or low 80s for some Oz stuff that offers "high mileage at high cost"), making it more complicated to do volumes.

 

[AccordV6MN]

I did some research for graduation paper back in the days on alternative fuel.

For E10 sold at the pump, it never has 10% of ethanol. Usually about 5-8% depends on the season. In summer, it’ll be about 7 -7.5% most of the time. And, in the winter, it’ll be about 5-6%. The alcohol content is reduced to help the fuel evaporates better. So in reality, gas station E10 will give up about 3% energy which should results in 3% less MPG.

During the research (E20 vs. E0, a million dollar research funded by bio fuel, of course) process, everything was tuned to +/-5% for E20 (tested every refueling) and absolute 0% in E0. I put both fuel in my 97 Escort. And, LOVE them both, use them separately. E0 gave me the mileage and E20 gave me power for the sluggish Escort. No dyno test but definitely can feel the power. I’ve never had any hesitation or any other ill effect on E20 but MPG. The actual test was the University fleet and my Escort is just for me to have fun.

My opinion in my Escort is personal. And, as any kind of paper out there, there is always people from the other side of the aisle will critique and discredit the research.

 

[y_p_w]

The thing is that E85 will give considerably better mileage in a flex fuel vehicle relative to the energy content. It's got a higher effective octane rating and most cars designed to operate on E85 will advance timing by a bunch.