Fuel Mileage

Discussion in 'Performance & Fuel' started by AzDragonLord, Dec 23, 2010.

  1. AzDragonLord

    AzDragonLord Rockstar

    I run E85 fuel about 99% of the time in my 2009 Sierra. I make a lot of trips between Phoenix and Los Angeles and my MPGs typically run between 15-16. I check my mileage each tankful using the calculator-method.

    I've tried a few things to see if I can get better mileage, like keeping my highway speed at 65 (vs 75) during one entire trip which kept the RPMs below 2000, but did not increase my mileage at all. I also installed cruise control which helps me, but did nothing for my MPGs. I did install a bed cover which gave me a whopping 1 MPG increase...not much but every bit counts. I'm not a lead-foot and I keep the (still factory) tires at the recommended 35 PSI.

    I was really shocked to see that keeping my speed limited to 65 did nothing to help with mileage! Could the AFM system be hindering the typical MPG saving techniques?
  2. Als09Sierra

    Als09Sierra Epic Member 5+ Years ROTM Winner 1000 Posts

    I run E85 too, and mostly run local roads back and forth to work (10 miles each way). I get about 10-11 MPG, which improves about 1-2 MPG running gas given the type of driving I do.

    My guess is that the majority of gas savings will come at acceleration, not at sustaining highway speed. Someone else who knows more about it will probably come along and have more ideas.
  3. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    15-16 mpg with E85 is pretty decent- it is like getting 20-21 mpg on pure gasoline.
    E85 has just 75% of the energy of pure gasoline
    16/.75= 21.3 mpg.
    Ethanol has just 70% of the energy content- by volume- of gasoline.(the 70% is from memory- if I'm wrong calculate it like this)
    .85 x .7=.595 +.15= .745 so E85 has ~75% of the energy of gasoline.

    16mpg/.75=21 mpg equivalent.

    You are getting good mpg.Whatever tricks you are using-they are working. 16 mpg on E85 is GOOD! Like getting 21 mpg on gas.

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