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What exactly does "Average" mean?

Discussion in 'Gen 2 Prius Fuel Economy' started by isipgas, Apr 8, 2008.

  1. isipgas

    isipgas New Member

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    In the consumption (bar graph) view on the vehicle information screen, I pay close attention to the Average mpg but wonder what it actually represents? I haven't reset it in many months, trying to get a more "true" measure of my overall mileage. Does anyone know how long its memory runs? Is it indefinite, or is something like your running average for the last 1000 miles?
     
    #1 isipgas, Apr 8, 2008
  2. morpheusx

    morpheusx Professor Chaos

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    It's indefinite meaning that its the mileage from the last time it was reset.
    Alot of people think it uses a complicated mathematical formula to calculate, but the formula is quite simple (number of miles since reset/amount of fuel used since reset) a quick note the number of miles since reset are not always the same as what is displayed as that number automatically resets when you add more then 3 gallons of fuel but doesn't reset the avg.
     
    #2 morpheusx, Apr 8, 2008
  3. F8L

    F8L Protecting Habitat & AG Lands

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    The older 2005 cars would auto reset the "average" MPG when you filled up (3ga or so?).
     
    #3 F8L, Apr 8, 2008
  4. pattom

    pattom Junior Member

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    When I fill up, I will reset the "Avg" and also the trip meter. I have an Excel spreadsheet that I am tracking my mileage. I compare the "Avg" mileage to the calculated mileage and have added total cost and overall mileage. I have noticed that the "Avg" and the calculated mileages are not always the same.

    I drive mostly on the interstate at 70 mph. After about 1900 miles I am getting 42 mpg. To me this is great !!!!

    Now can someone explain the "Bars" on that screen.
     
    #4 pattom, Apr 9, 2008
  5. JimN

    JimN Let the games begin!

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    The bars are the average mpg over that 5 minute period. I prefer seeing the instantaneous mpg but I do peek when stopped at the traffic lights.
     
    #5 JimN, Apr 9, 2008
  6. Prius 07

    Prius 07 Member

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    If you want to keep your "average MPG" MFD reading don't be surprised if during a service call it gets reset to zero. The dealer will disconnect the battery in some service of the Prius. Your clock will be off and your MFD settings will be erased.
    Personally I like to reset my MFD MPG after every fill-up and maintain my lifetime numbers in a spreadsheet (not much effort). For me and many others current MFD MPG readings are more relevant and useful.
     
    #6 Prius 07, Apr 13, 2008
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