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Mileage at beginning of tank

Discussion in 'Gen 2 Prius Main Forum' started by jkash, Sep 28, 2006.

  1. jkash

    jkash Member

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    2004 Prius
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    For over two years, I have been mystified by something about my Prius. Why does the mileage I get in the first 50 miles of a tank effect the mileage for the entire tank so much? With about 320 miles on this tank, my display reads over 58 mpg. I am usually not that close, more like 53 to 56. I started this tank in a good way driving my trip from the San Fernando Valley to the West Los Angeles. It is almost all down hill. The car read over 70 mpg when I got to my destination, about 20 miles away. If I start off a new tank with some short stops, I have a very hard time getting the mileage back over 50 by 300 miles.

    Anyone else experiencing this?
     
    #1 jkash, Sep 28, 2006
  2. Renocat

    Renocat Member

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    Three
    <div class='quotetop'>QUOTE(jkash @ Sep 28 2006, 09:02 PM) [snapback]325342[/snapback]</div>
    I had something similar happen the tank before this one. I had driven 15 minutes or so and stopped to get gas. I reset the mpg. I drove 2 minutes to pick up my daughter and then drove 45 minutes through rural/town/city driving to an appt. My MPG was at 60.1---my highest ever. The tank finally averaged out at 52---close to my regular MPG

    If I fill up and drive home and park the car overnight then take my usual commute to work, I have to work hard to get that tank up to my ~50 MPG
     
    #2 Renocat, Sep 28, 2006
  3. obtuseangler

    obtuseangler New Member

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    I believe that what you are experiencing is nothing more than the effect of averaging rather than a computer oddity. Early low mileage will pull your average down just as early high mileage will pull the average up. It's easy to verify this by clearing a tripometer when you fill up and dividing the accumulated mileage by the gallons needed to fill the tank, then checking this against the mpg on your screen.

    I'm just a math teacher nerd, not an engineer, so could be way wrong.
     
    #3 obtuseangler, Sep 28, 2006
  4. hdrygas

    hdrygas New Member

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    Let us look it like this! You are a freshman at high school or collage, and there are two scenarios: first you are hot to trot, warmed up and ready to go. You are focused on your goals. Second you are like at school and away from your parents. You are free, and you are a party on dude (or dudet). At the end of the semester ( I came from a semester college) one has a 4.0 the other a 2.1. You all can do the math on that one. How long will it take you to change all of those D's so you can graduate with your class?
     
    #4 hdrygas, Sep 28, 2006
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