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Summer gasoline formulation vs MPG

Discussion in 'Gen 3 Prius Fuel Economy' started by bill french, Apr 13, 2011.

  1. bill french

    bill french Junior Member

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    IV
    On Saturday, I filled my 2010 PriusIV at the Hess station in Chichester, NH. Every day since, my indicated MPG has gone up about one MPG, with my 40 mile round trip to work.
    I had been running around 46-48 MPG indicated this winter. Monday it was up over 50. Yesterday 52, today it is up to 53 mpg and I have used 1/2 tank on 256 miles, which is much better than my winter stats. I can only guess that Hess started pumping a different gasoline this week as I can think of no other variables over the same closed daily route.
     
    #1 bill french, Apr 13, 2011
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Could it be warmer out?
     
    #2 JimboPalmer, Apr 13, 2011
  3. F8L

    F8L Protecting Habitat & AG Lands

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    Has the temperature changed as well?

    Between higher temps and summer blend fuel, most of us see much higher MPG than in the winter. This includes a reduction in foul weather which hurts fuel efficiency for everyone. Unfortunately most vehicles get such poor MPG that they never notice the 2mpg drop (from 20 to 18). It just looks like a much larger drop in the Prius because of a higher MPG number but 10% is still 10%. ;)

    Fortunately for us, the 10% drop translates to a larger MPG number change (50mpg to 45mpg) BUT because the Prius is so efficient, the resulting loss is still less expensive than those going from 20mpg to 18mpg. Lets do some math based on a 20,000 mile/yr average. I'm using this because that is what I used to average. I drive more now.

    10,000 miles / 50mpg (summer) = 200 gallons * $3.50/ga = $700
    10,000 miles / 45mpg (winter) = 222 gallons * 3.50/ga = $777
    vs................................................................................... $77

    10,000 miles / 20mpg (summer) = 500 gallons * $3.50/ga = $1750
    10,000 miles / 18mpg (winter) = 556 gallons * $3.50/ga = $1944
    ............................................................................................$194

    Sucks to be the 20/18mpg driver doesn't it? lol
     
    #3 F8L, Apr 13, 2011
  4. krelborne

    krelborne New Member

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    I, too, am noticing a remarkably better tank this time (60 MPG, versus lower 50s being the previous norm and a previous high of 56.7 with no ethanol). I filled up on March 31st. It's probably a combination of factors (getting better at driving it, warmer temps, etc), but I suspect the gas is different as well.
     
    #4 krelborne, Apr 13, 2011
  5. bill french

    bill french Junior Member

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    IV
    Yes, we have had some really warm weather in NH the last few days, so it's probabably a combination of fule blend and weather. Engine warmup seems to be happening more quickly.
     
    #5 bill french, Apr 13, 2011
  6. alfon

    alfon Senior Member

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    I have seen a drop of 60 degrees to 45 degrees with rain weather drop my mpg by 10 mpg's.

    This happened in one day in the Northwest during the spring of 2010.

    Temps were in the low 60's, clear and dry, later on in the day a cold front moved in with temps in the mid 40's and rain.

    During the nice weather mpgs indicated were about 60 mpg, when the weather changed about 50 indicated.

    al
     
    #6 alfon, Apr 13, 2011
  7. airgas1998

    airgas1998 New Member

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    gee i feel so sorry for you nw'ters. try going from 80 to 40 overnight. or winter in general where it can get to -20-30 below.:)
     
    #7 airgas1998, Apr 13, 2011
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