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I'm getting 27 MPG and it's hardly crawling up?! (Details inside)

Discussion in 'Gen 2 Prius Main Forum' started by macmaster05, Sep 30, 2009.

  1. macmaster05

    macmaster05 Senor Member

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    I just bought a new used Prius (a loaner car) with 10,000 miles on it. I've only put on 20 miles so far. My average MPG on the display lists 27.8 mpg, and rising EVER SO SLOWLY - maybe .1 mpg every 10 minute drive.

    My question is, why is this number so low? Can I erase my trip information by pressing Reset so that it will start off at zero and then go reasonably higher after I start driving (assuming I don't drive at 27 mpg thereafter).

    I have a suspicion that my average mileage is low because it is averaging it based on the 10,000 miles my car has when the previous rental owners didn't take care of it and got terrible mileage - but I know this shouldn't be the case if the Trip is frequently reset, but is it possible?

    Or was I just a really bad driver in my first 20 miles? Then how long before it goes up top 45+. (I'm not that bad of a driver - in fact my mom drove it a bit and it still doesn't go up and she's a pro).
     
    #1 macmaster05, Sep 30, 2009
  2. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    The Prius gets ~25mpg for the first few minutes to warm up the catalytic converters. If you watch the histogram, you'll see the mileage increase after 5-10 minutes or so.
     
    #2 a_gray_prius, Sep 30, 2009
  3. macmaster05

    macmaster05 Senor Member

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    I thought, however, that if I only had 10-20 miles on this trip, then whenever I average maybe 50 mpg during a drive, the average should shoot up from ~27 to 35+. It still hasn't done that. Instead it goes up from 27 to 27.1 when I have a good 10 minute drive. Make sense? Thanks so much...I'm worried somethings not working...
     
    #3 macmaster05, Sep 30, 2009
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    If you 'reset' the trip odometer and 'reset' the touch screen showing your average mileage, then the new average should change rapidly at first, as you are dividing small numbers by small numbers. (1 mile by 1/40 of a gallon) If you never reset either, then you are dividing about 10000 miles by about 370 gallons, and the effect of what you did in the last mile is pretty much lost. (10000 +1 by 370 + 1/40)
     
    #4 JimboPalmer, Sep 30, 2009
  5. macmaster05

    macmaster05 Senor Member

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    Hey Jimbo, that seems to make sense. You understood what I was asking. It just so happens that today I did reset the Trip Odometer to zero (Trip A was ~5000 miles, so was Trip B ). but I did NOT yet reset the touch screen. You're saying I need to do both and I hope that's the answer too.

    I will hit reset on the touch screen and let you know but always feel free to give me feedback and help. I'm new at the Prius haha. Thanks again.
     
    #5 macmaster05, Sep 30, 2009
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Reset the Consumption Screen on the MFD. That'll get the average fluctuating wildly lol. (until it averages out over more miles of course)
     
    #6 Tideland Prius, Sep 30, 2009
  7. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    What I 'think' is happening, is that resetting the trip odometer only resets the mileage shown on the touch screen, it does not reset the mileage used to compute an average. the Reset on the touch screen does that.

    As the average per tank interests me the most, I do them both at once.
     
    #7 JimboPalmer, Sep 30, 2009
  8. grand total

    grand total Member

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    Resetting the trip odometer only resets the trip odometer, it is completely independent of the mileage shown on the MFD (touch screen). Macmaster05 needs to reset the mileage shown on the MFD.
     
    #8 grand total, Sep 30, 2009
  9. macmaster05

    macmaster05 Senor Member

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    I reseted MFD. Have driven another 20 miles today. Average consumption is at 53.3. That's more like it! Thanks everyone.
     
    #9 macmaster05, Sep 30, 2009
  10. hill

    hill High Fiber Member

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    Yep!
    When all else fails ... read the handbook
    ;)
    or ask here
     
    #10 hill, Sep 30, 2009
  11. macmaster05

    macmaster05 Senor Member

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    Yup. I was afraid to press Reset on the MFD, however, since I was in the middle of my trip. Well, only 20 miles in, but still. I'll just have to remember to add 20 to whatever I finish my tank with.
     
    #11 macmaster05, Sep 30, 2009
  12. Frayadjacent

    Frayadjacent Resident Conservative

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    20 miles is definitely not enough to ascertain what kind of fuel economy the car, and you driving it, are capable of achieving.

    Heck, 20 miles is barely warmed up.

    Short trips will kill your mileage, because as mentioned earlier, when the engine is warming up, mileage sucks. This is true of any car.

    Hitting the reset button on the Consumption screen will reset the trip gauge and the economy, and will start averaging it again. If you do this when the car is cold, expect low numbers, but they should climb pretty quickly. Depending on your commute, it's entirely possibly you may have a (relatively) low average economy. The car doesn't like short trips.
     
    #12 Frayadjacent, Sep 30, 2009
  13. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    :clap2:

    Yeah, on the 2004/05 the MFD reset every time more than three gallons of gasoline were pumped into the tank. Toyota must have guessed that people wanted to have it automatically reset. The problem is that people apparently actually wanted a lifetime average. So Toyota changed it so that if you want per-trip average, you can hit it yourself. If you want lifetime average, just don't hit it.

    Glad you got it figured. 53mpg is pretty respectable for only a few hundred miles.
     
    #13 TonyPSchaefer, Sep 30, 2009
  14. macmaster05

    macmaster05 Senor Member

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    Yeah, I actually like the idea of not pushing reset and getting a lifetime average - now that my average is decent. I think a lifetime average is a little more accurate since you don't have to "re-earn" your mileage after buying gas.

    But I hear that whenever you buy gas (any amount) the miles automatically clears to zero. I dont know because I havent bought gas yet, and don't plan to for quite some time.
     
    #14 macmaster05, Sep 30, 2009
  15. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I have an '04 so hopefully someone else can confirm the mileage reset.
     
    #15 TonyPSchaefer, Sep 30, 2009
  16. snead_c

    snead_c Jam Ma's Car

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    Do some reading here on PC about your car. It's a great auto but needs to be understood if you want to fully enjoy it's strengths as well as anticipate its issues. You might want to search :
    Fuel tank bladder and filling
    tire air pressure
    jump starting issues
    any threads on how the engines work
    etc, etc, etc....:welcome:
     
    #16 snead_c, Sep 30, 2009
  17. Frayadjacent

    Frayadjacent Resident Conservative

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    That works great in the 09... until your friend, who is fascinated with how it works starts poking around... and hits the reset button. :|
     
    #17 Frayadjacent, Sep 30, 2009
  18. Tideland Prius

    Tideland Prius Moderator of the North
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    Yup. My '05 resets after every fillup.
     
    #18 Tideland Prius, Sep 30, 2009
  19. richard schumacher

    richard schumacher shortbus driver

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    If you did not get them with the car, buy copies of the 2009 Owner's Manual and the Scheduled Maintenance Guide. Both of these are written by Toyota, not by a dealer; dealers should have them both or they can be found online. They are filled with stuff you need to know and will save you bother and money.
     
    #19 richard schumacher, Oct 1, 2009
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