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2009 - 26 MPG but display says 44.6 - HELP!

Discussion in 'Gen 2 Prius Fuel Economy' started by FloridaFazz, Nov 19, 2008.

  1. Celtic Blue

    Celtic Blue New Member

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    No, I'm in the midwest. He must be thinking of someone else. The closest I've been was doing some work for Shell in Anacortes, WA a few years ago, and that was just a few days each time.
     
  2. richard schumacher

    richard schumacher shortbus driver

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    Actually, that's backwards: the fuel tank bladder and gas gauge variabilities make the *manual* method less accurate, not the MFD. The MFD does not use the fuel gauge to calculate MPGs. The MFD counts actuations of the fuel injectors, which are well-calibrated and operate from constant pressure; they have to be accurate in order to keep the fuel/air mix correct.

    Also note that gas stations have an economic incentive to make their pumps inaccurate on the high side, which makes manually calculated MPGs too large.
     
  3. jennsdad

    jennsdad New Member

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    This is my favorite subject.
    Bottom line, if you follow the owner's manual, and the advice of the consensus here, you will NEVER be able to compute accurate MPG. The fuel management system is simply a rough guide (very rough) and you will never get the same answer twice. Unless you opt to make sure that the tank is full every time. A subject of a separate thread.
    My experience over the last 5+ years has been that the fuel guage is a suggestion only. One would think that rational people could safely assume that when the low fuel warning arrives (flashing last segment, light, whatever) ONE WOULD HAVE AT LEAST A USEFUL HALF GALLON LEFT. Wrong. That would allow you, even as a leadfoot driver, at least 16 miles to refuel. Wrong. The system shuts you down way sooner than that. As little as 5 miles after the last segment started flashing, in one instance.
    Once you get used to both filling up consistently and noting the mileage carefully, you can ignore the guage and go with the odometer. I used the B trip odometer exclusively to keep track of that.
    Unless something is truly wrong, 42-45 MPG should be easily routine.
     
  4. snead_c

    snead_c Jam Ma's Car

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    Also remember that how you drive can make a significant difference in fuel consumption. Short trips, aggressive driving, high speeds, Toyota recommended air pressure, car load, and cold temp induced engine warm up all can lower MPG. All these items are discussed in various links on the web site.
    I trust the MFD to be accurate enough for the real world and always try to slowly fill up at one half tank empty. I'm averaging 46+ mpg over my first 4400 miles.
    Enjoy !