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How is MPG Calculated?

Discussion in 'Gen 2 Prius Main Forum' started by johnnieliu, May 3, 2006.

  1. johnnieliu

    johnnieliu New Member

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    How does the Prius calculate MPG?

    Does the Prius actually measure fuel consumption or does the MPG calculation come from the volume sensors in the bladder? Obviously one is more accurate than the other.

    Thanks.
     
    #1 johnnieliu, May 3, 2006
  2. qbee42

    qbee42 My other car is a boat

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    <div class='quotetop'>QUOTE(johnnieliu @ May 3 2006, 12:43 PM) [snapback]249074[/snapback]</div>
    It measures fuel consumption. The engine controller knows exactly how much fuel is being injected.

    Tom
     
    #2 qbee42, May 3, 2006
  3. johnnieliu

    johnnieliu New Member

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    <div class='quotetop'>QUOTE(qbee42 @ May 3 2006, 10:38 AM) [snapback]249134[/snapback]</div>
    That's the answer I wanted to hear! The last time I filled up before yesterday, the temp was around 42-45 degrees F. The temp yesterday when I filled up was about 61 degrees F. I know that the fuel bladder grew since I put in almost 10 gallons on 460 miles traveled. Previous fill-up was only about 9 gallons. Computer MPG read around 51 MPG, which was much higher than hand calcs. Thus the concern about whether the computer was accurate.

    THANKS!
     
    #3 johnnieliu, May 3, 2006
  4. Sufferin' Prius Envy

    Sufferin' Prius Envy Platinum Member

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    <div class='quotetop'>QUOTE(johnnieliu @ May 3 2006, 11:23 AM) [snapback]249163[/snapback]</div>
    For more accurate hand calculations you really need to use multiple fill-ups. Calculating after ten fill-ups, rather than after only one, decreases the margin of error caused by not being able to exactly replace the fuel used - due to fuel bladder expansion/contraction issues.

    Fill-ups #2 thru #9 really don't matter if the tank was fully topped. Just add the pumped number of gallons. Start with a full tank and end with a full tank on fill-up #10.
     
    #4 Sufferin' Prius Envy, May 3, 2006
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