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MDF vs hand cal variance with top offs vs fill ups.

Discussion in 'Newbie Forum' started by NinnJinn, Feb 22, 2012.

  1. NinnJinn

    NinnJinn Member

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    I have driven my Prius over 1500 miles in the last 2 weeks. I have noticed that if I top off my tank, (3 pips or more left) hand cal vs MFD is about 1.5-2mpg off. Yet there has been twice my car "dings" and the last pip is flashing. When this happens, I find that MFD vs hand cal is always 5+mpg difference.

    Just curious if this happens to anyone else?
     
    #1 NinnJinn, Feb 22, 2012
  2. F8L

    F8L Protecting Habitat & AG Lands

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    Try to resist the tempatation to top off the tank. With a bladder system you risk overfilling and either:

    A: Cause the bladder to over-expand then retract and push fuel back out which results in you standing in a puddle while gas spills out of the filler neck for 5-10 minutes.
    B: You overflow into the emission system components and cause expensive damage.
     
    #2 F8L, Feb 22, 2012
  3. NinnJinn

    NinnJinn Member

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    So basically I need to just wait until I'm down to the last pip then? I always have this fear I am going to run out of fuel. The least amount of fuel I have put in was 4gals. 2 were over 8gals, a 7 gal and a 6. Except for 1 they have all had at least 250 miles since last fill up.
     
    #3 NinnJinn, Feb 22, 2012
  4. F8L

    F8L Protecting Habitat & AG Lands

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    I would never make such a suggestion because each situation is unique and only you can determine when you should fill up. I fill at 1-2 pips usually but I generally get 360-500miles to a tank. Filling up every 250 miles kinds sucks but I think running out of fuel would suck worse..... Unless a bus full of Hawaiian Tropic girls stopped to help you.
     
    #4 F8L, Feb 23, 2012
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    There's no reason to stretch a tank, except for (dubious) bragging rights.

    I fill up anytime we're near our usual station and the tank is less than half. I fill till it does the auto shut off, and don't try for any more.

    As far as calculated vs displayed mileage, our displayed mileage is consistantly optimistic by about 7%. I use it as a rough gauge as the tank progresses, but rely on calculated.
     
    #5 Mendel Leisk, Feb 23, 2012
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