E85 vs E10(gas+10%ehtanol)

[brandonppr]

Ok so I have ran 3 tanks thru my 2011 2.4 Malibu of E85 and it seems to get terrible millage on E85. Does this have something to do with it being a smaller engine or lighter car? I used E85 vs Gas when I had an Escalade 6.2L and the differnce was not that much and E85 was even slightly better MPG when towing than gas.

So with the same trip and same driving style doing a trip that I do often wich is about 20 mins long using EOC the whole way the best I can do on E85 is 30mpg. After switching to E10 I can get 50mpg. Also I'm sure there was still some E85 still in the tank. I think about 2 gallons in a 16 gallon tank. So I expect to get even better on my next fill. I might even try 100% gas if I go by the station that sells it when its getting close to E.

[Frank Lee]

You can get 50 but your fuel log entries say 16.

[brandonppr]

Originally Posted by Frank Lee

You can get 50 but your fuel log entries say 16.

My fuel logs are from using E85.

I'm going by the DIC reset when I left my house till I get back on the house. About a 20 min drive. I have not filled the tank yet since switching to E10. I won't have a log entry for that until I fill up in a few days. Also me and my wife drive this car. She doesn't drive to save fuel and lets the car idle alot when she is waiting for something. So it kinda kills my log. So I have been reseting the DIC when I drive till I get home to see what I can get. It has been pretty acurate overall because it will vary +-1mpg from actual.

I just bought the car about a month ago and have only ran E85 until the last fill.

[Frank Lee]

The fe difference between E10 and E85 is nowhere near that great.

[brandonppr]

Acording to EPA its rated
E85
15 city
18 combined
23 Hwy

Gasoline
22 city
26 combined
33 Hwy

Thats about 44.5% better on Gasoline
Why is there so much differnce?

[Frank Lee]

I don't know.

My fe using E85 doesn't drop that much and my stuff isn't even flex fuel.

[Daox]

Sounds to me like they did a bad job optimizing the engine for E85. No real big surprise there. Its a different fuel that requires a fairly different engine design to make it run efficiently. Gasoline likes lower compression ratios around 10-13:1 where as Ethanol likes 17:1 or more. Flex fuel vehicles are a big (IMO stupid) compromise. You can't design an engine to run efficiently on two different fuel types that require different engine designs.

[PaleMelanesian]

E85 has about 72% the BTU of straight gas.
18 mpg combined is 69% of 26 mpg combined.
30 mpg actual is 60% of 50 mpg actual.

Yeah, sounds like it's better optimized for gas than for ethanol. Still, not far off from the theoretical numbers.

[JPD]

Originally Posted by brandonppr

Acording to EPA its rated
E85
15 city
18 combined
23 Hwy

Gasoline
22 city
26 combined
33 Hwy

Thats about 44.5% better on Gasoline
Why is there so much differnce?

Hi, I live in Thailand where E10 is the most common fuel. Manufacturers of flex-fuel cars such as the Chevrolet Captiva all claim E85 to give 40% less mileage. E85 gives lower mileage as ethanol is less energy dense than gasoline; I was surprised to read that your Escalade had better towing MPG on E85, I can't explain that.

[roosterk0031]

My wifes 2010 Impala does about 24.5 E85(last 3 tanks), 28-29 with E10 with her driving(about 15% reduction). E85 ratings of 14 mpg city, 22 hwy, 17 combined. (I need to run 3 tanks of E0 thru it to get that baseline)

Her previous suburban did 12.5 E85, 15 E10 also about 16% reduction (see Fuelly 2002 suburban, separate fuel log for each fuel use)

At current local prices E85 is just barely cheaper per mile with the Impala. ($3 vs about $3.60 gallon).

When changing fuels, or making my own blends it takes the computer a little while to adjust the fuel trim, making it impossilbe to do A B A test IMO, best to run 3-4 tanks of each thru to get a multiple tank average for good data.