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Prius Mileage Change?

Discussion in 'Gen 2 Prius Main Forum' started by canon, Jun 22, 2006.

  1. canon

    canon New Member

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    I am really puzzled. I purchased my '05 Prius in August '05. It took a month or so to learn how to drive it for maximum mileage. After the first several weeks my mileage consistently was 54-55-56. It stayed that way until the last tank(June 22) and for some unknown reason it has dropped to 43.6 mpg. I check the tire air pressure every tank full and maintain at 42F/40R. I just filled up today and the first 5 miles I was averaging 65mpg and when I pulled into a shopping center I glanced at the average MPG and it dropped to 22mpg. After another 10 miles it is around 29-30mpg. I have never seen it that low.

    I have 9000 miles on my Prius and I don't have a clue why this sudden change. I don't know if it's the electronics on the dash or something wrong with the synergy drive. I am really puzzled.

    If anyone can share their opinions, thoughts and directions I would greatly appreciate. My plan is to drive it for a few days and take it to the dealer.

    Your input is appreciated.
     
    #1 canon, Jun 22, 2006
  2. richard schumacher

    richard schumacher shortbus driver

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    Results over the first 10 miles mean next to nothing. This may also be your first tankful of 10% ethanol summer formulation. Drive a couple more tanks and see what happens.
     
    #2 richard schumacher, Jun 22, 2006
  3. efusco

    efusco Moderator Emeritus
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    That means absolutely nothing that early into a fill up/tank. Drive it another 100 miles and if it's still low let us know. One long stop at a light with the ICE running b/c of the AC could drop it that low with only a few miles on the tank.

    Be sure to check the tire pressure though, the cases that I've personally had where there was a sudden persistant drop in mileage for 25-50 miles it was due to a low tire.

    See, also, this other related thread posted earlier today:
    http://priuschat.com/index.php?showtopic=21140&hl=
     
    #3 efusco, Jun 22, 2006
  4. canon

    canon New Member

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    Thanks. I just checked the air pressure this morning and I had to add one pound in the front left and that's it. All the others were spot on. I have never seen less than 43 mpg on this car. Normally when the tank has just been filled there can be a dramatic ship in the computer's calulation of mileage but I have never seen it drop to the 20's.

    I will drive it more to see if it increases but knowing how it has registered in the past and the dramatic change leads me to believe that there is something wrong.

    THanks for your input.

    Bob




    <div class='quotetop'>QUOTE(efusco @ Jun 22 2006, 04:24 PM) [snapback]275421[/snapback]</div>

    I don't know if they mix ethanol in the fuel in North Carolina. If they did it would have had the same impact when I bought the car last August when the fuel mileage was consistently over 50mpg.

    Thanks for your input.




    <div class='quotetop'>QUOTE(richard schumacher @ Jun 22 2006, 04:24 PM) [snapback]275420[/snapback]</div>
     
    #4 canon, Jun 22, 2006
  5. efusco

    efusco Moderator Emeritus
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    They now add ethanol nationwide...it replaces MTBE that they used to use. Most speculation puts it b/w 3-5% blend unless you already use E10
     
    #5 efusco, Jun 22, 2006
  6. mssmith95

    mssmith95 Michael

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    Bob, a few quick notes

    Please update your profile to include your location and package so we can better know how to respond. Thanks! :D

    I also have around 9700 miles on my 06, and I have noticed occasional changes from tank to tank...but most can be explained.

    1. Air conditioning - even using it a little can knock 5+ MPG off of your average
    2. EV mode - if you use it too much
    3. Oil changes - for some reason I get worse MPG for the first 100-150 miles after each oil change - however, it always seems to "catch up" by the end of that tank. I can't quite expain why this happens, but with all 3 oil changes it has happened!
    4. Bad fuel or change in fuel mixture (already noted by others)

    I assume that your are checking your tires in the morning before you drive rather then when you are filling up? If your are doing it when filling up, that could explain how your readings look the same but are actually lower then when it was colder outside (the warmer temperatures would increase your readings even higher then normal).

    I agree with others, give it a little to see if it averages out.
     
    #6 mssmith95, Jun 23, 2006
  7. richard schumacher

    richard schumacher shortbus driver

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    <div class='quotetop'>QUOTE(canon @ Jun 22 2006, 03:33 PM) [snapback]275423[/snapback]</div>
    Nationwide use of ethanol as a replacement for the fuel oxygenator MTBE started in June 2006. Minnesota and a few localities were requiring it before then. Otherwise it's unlikely that you were getting gasoline with ethanol unless you were looking for it explicitly. Now you can't avoid it.
     
    #7 richard schumacher, Jun 23, 2006
  8. dpower

    dpower Member

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    <div class='quotetop'>QUOTE(richard schumacher @ Jun 23 2006, 10:40 AM) [snapback]275809[/snapback]</div>
    In Texas they are only required to blend ethanol in non-attainment areas (Dallas-Fort Worth, Houston) that have poor air quality and need additional oxygenation, though it might end up in other areas depending on the delivery route.
    I have found several times when my MPG drops below 50 that a bottle of injector cleaner ( I use the Chevron brand) brings it right back up to the mid 50s, it could be that the engine is very sensitive to any degradation.

    There is some concern that as ethanol is introduced into the distribution chain that it would clean out the accumulated gunk (its a very good solvent) and it would end up in your gas tank. I’m getting my fuel filter changed with every other oil change for the next year or so just in case.

    David
     
    #8 dpower, Jun 25, 2006
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