E85 MPG TEST
 

Okay so finally i am on an E-85 tune and I've decided to do a MPG test to see whats the difference. I got to enjoy the tune a little so now its time to grandma the tune a little and see how it compares to regular pumpgas.
For reference on pumpgas i get around 30-33mpg with the highest being 38mpg on an all highway trip not going past 60mph and shifting around 2500-3000rpm. Im going to be using the torque app to obtain some data and at the end of the day i will update the thread with all the data i took. Just doing this for myself really, but i know there are others that are really curious to see whats the most MPG this car can get on E-85. My estimate is 24mpg, so here we go. Not going to drive anymore today so heres my first update.

Gas Station:Sunergy
E-85:$3.279
93 Octane:$4.039
Gallons filled:10.670
Total Price:34.99
Total Price if using 93:$43.10
Savings:$8.10

Day 1
highway/city: 30/70
Temp: 41F
Miles Driven:20.9
Highest Speed:65.3
Average Speed:33.1mph
Highest rpm:3,432
Avg MPG Display:20.2

Day2
highway/city: 80/20
Temp: 42F
Miles Driven:51.0
Highest Speed:68.7
Average Speed:44.1mph
Highest rpm:3,811
Avg MPG Display:24.2

http://www.ft86club.com/forums/pictu...pictureid=3101




So this is where my gas meter is at after 50 miles. Usually im around 70-90 miles at this point on pumpgas. So now my Guess is a little lower now and im thinking 21-22mpg on E-85. Im really hoping for 24-25

Updated!

Day 3
highway/city: 90/10
Temp: 38F
Miles Driven:149.4
Highest Speed:74.8
Average Speed:56.6mph
Highest rpm:6,783
Avg MPG Display:24.9

Sorry i didnt take a picture but i just past the halfway mark on the fuel meter. While the results dont look promising i decided to check the fuel percentage(from ecu) and it reads around 66-71% still left in the tank, which means that even tho my fuel meter is below half i still have more fuel than i think i do. So my estimation had changed and my guess is that im going to end up with around 25-27mpg which would be a win in my books if it can really pull that number

day 4
highway/city: 80/20
Temp: 36F
Miles Driven:228.1
Highest Speed:62.9
Average Speed:38.0mph
Highest rpm:4,468
Avg MPG Display:20.9

So my gas light is about to come on very soon and i think i can squeeze out another 30-40 miles before i have to fill up. Tomorrow is the day i find out what gas mileage i will be getting from e-85. im really thinking 24-25 mpg and im wondering if the gas mileage could get better with warmer weather.

If your light is about to come on and you've already done 228 miles, it's most likely going to be in the 20-22 mpg range. My car takes over 10 gallons when the light comes on.

its weird tho cuz when i check the fuel level im still showing 35%...going to reset the ecu and see if the fuel level goes up a little...but im going to see if i can put a little more miles down before i fill up...we will find out tomorrow tho...

I wouldn't trust the level % more than the fuel gauge needle.

The energy density of E85 IS lower than gasoline so a drop in mileage is expected (basic chemistry here folks). I'd like to see the math on whether or not the price difference (and power difference :burnrubber:) makes up for the drop in mileage. E85 is about $3.30/gal at the station nearest my house, while premium is from $3.60/gal to $3.90/gal depending on which station we're talking about.

Agreed. Really what I would trust is your trip meter/odo. Drive a set amount, fill up, calculate mileage based on miles driven divided by gallons filled up; boom gas mileage.

Totally correct. That is the way to know EXACTLY what is your MPG.

Well im doing the test accordingly but its already been discussed that the fuel guage is a little off on our cars. There was a point where if u had a tune u had a fuel level percentage meter but it was stopped because it was upsetting the gas meter. i wud trust more what the ecu says rather than the gas meter. But tonight i might drive out and see when the gas light comes on a fill up and see whats the actually mpg i get.i think i can get another 20-25 miles before it comes on.

just took of the negative cable from the battery to reset the ecu and see if the fuel meter shoots up a little. gonna wait 5-10mins and see what happens..

Usually e85 would have to be approx 30% less than the price of gas to make up for the lower mpg's. Fun factor not included.

Just reset the ecu and the guage did go up..i should have a took a before and after pic but basically the the needle was in between E and the first mark and now its sitting right before the first mark..so maybe i can push a little more miles out before the light comes on

Your fuel pump hates you.