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over the past month or so I have been experimenting with E85. I have been running my tank down till the low light comes on then I have been filling up with 3.0 gallons of E85 and then toping off with 91 (the highest octane available here). My results have been fairly consistent over the time period. I would like to note that i only try for good fuel mileage during the work week, my driving habits on the weekend include alot of idling and stopping and going, that being said i have not gotten below 31mpg on my weekend. My driving habits on the weekdays are 92% highway. On the highway i set cruise at 55-57 mph and then take it easy in the city. The picture below is right after a fill up, this is from my work week.




If i calculate the mileage with total amount of fuel it equals 45.4
 

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...the DIC display is typically slightly "optimistic" because the ECM seems to slightly under-estimate total fuel (GALS) consumed.

...luckily both you and the DIC/ECM use the same milage (MILES) numbers from Trip#1 or Trip#2; although, measurements show even that number is slightly 'off' too:

...welcome to the 'fool economy' club!

...your GPS milage seems to be pretty accurate, because when Car & Driver did their Cruze LTZ tests, one of the measurements they made was: one OdoMile = 5,317 feet. That's 37 feet too long, indicating the odometer readings are 0.007% too high (1.0070 = 5317/5280), which matches up with your milage numbers (1.0050 = 1698/1689) pretty well.

...and your DIC/actual fuel ratio ( 0.94 = 54.5/58.2 ) is also very close to what I've been tracking ( ~0.95 ).
...thus, MILES are slightly high and GALS are slightly low, and cause the "optimistic" MPG values shown on the DIC display.
 

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shawn672 -- now there's a good question for Vince: can the 1.4LT be remapped / tweeked to run on E85 reliably--assuming warranty is no longer an issue?
 

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shawn672 -- now there's a good question for Vince: can the 1.4LT be remapped / tweeked to run on E85 reliably--assuming warranty is no longer an issue?
The real question is, can the fuel lines and components support the ethanol... tuning wise anything can be done. LNF's and LSJ's are running e85 with Vince's tuning
 

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...Thanks, Shawn! -- I'll take that as a "Yes."
 

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Your basically running a e15 to e20 blend that may yield a slightly higher octane than 91 but, if you ran the straight 91 assuming it was pure gas, then you would get better off the pure gas, as the btu of the ethanol is lower ,and therefore requires more fuel to keep from running lean. I think an e85 conversion other than for performance will be a catch 22. You will get better power off the proper tune, but still yield close to 25% decrease in mileage.
 

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Your basically running a e15 to e20 blend that may yield a slightly higher octane than 91 but, if you ran the straight 91 assuming it was pure gas, then you would get better off the pure gas, as the btu of the ethanol is lower ,and therefore requires more fuel to keep from running lean. I think an e85 conversion other than for performance will be a catch 22. You will get better power off the proper tune, but still yield close to 25% decrease in mileage.
...you're 100% correct, but the premiss is that possibly the lower co$t of E85 fuel can/will offset the loss in economy...especially since higher octane (116 for E100) coupled with high compression (turbo-boost) can recover some (but never all) energy lost due to reduced BTU content.
 

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...you're 100% correct, but the premiss is that possibly the lower co$t of E85 fuel can/will offset the loss in economy...especially since higher octane (116 for E100) coupled with high compression (turbo-boost) can recover some (but never all) energy lost due to reduced BTU content.
My brain hurts! It was so much simper with a carburetor and avgas.
 

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...it's simple really: "...which co$ts more, the Chicken or the Egg?"
 
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