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calculated vs. computer MPG - Please post your results

Discussion in 'Gen 3 Prius Fuel Economy' started by F8L, Jul 10, 2009.

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  1. pakitt

    pakitt Senior Member

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    The MFD will update the display of average fuel consumption also when you are not moving, whether you are in park or drive. Essentially the MFD does take into account fuel consumed from the ICE in all conditions.
    Moreover, pumping to the brink or stopping at the first stop, will change the calculated percentage wrt the MFD, but it will also vary from time to time.
    In EU, from first stop to "full to the brink" (you see gas in the tube), is about 0.5L/0.125gal or maybe a bit more (I think it depends on how the pumps are calibrated). Over 30-35L/8-9gal, that is about a 1-2% difference. This also why likely my average is about 6-7%, instead of 5-6% - I always fill it up to the "brink", i.e. I never stop at the first stop, but add another couple.
     
    #781 pakitt, Apr 2, 2012
  2. Codyroo

    Codyroo Senior Member

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    OK, my car is now 2 years old!

    Over 2 years and 44970 miles tracked.....

    Displayed MPG = 62.8
    Calculated MPG = 59.4
    % Difference = 5.8%
     
    #782 Codyroo, Apr 5, 2012
    1 person likes this.
  3. F8L

    F8L Protecting Habitat & AG Lands

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    I don't know how you do it but those are awesome numbers, bru. :)
     
    #783 F8L, Apr 5, 2012
  4. Dog Face

    Dog Face New Member

    Joined:
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    Location:
    CT
    Vehicle:
    2012 Prius
    Model:
    Four
    Last tank:

    326.3 miles
    Gas used: 5.675 gal
    Displayed: 61.3 mpg
    Calculated: 57.50 mpg
    Error: 6.6% or 3.8 mpg

    Price: $4.129/gal !!
    sonofabitch!
     
    #784 Dog Face, Apr 6, 2012
  5. edroun

    edroun New Member

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    Location:
    Omaha, NE
    Vehicle:
    2012 Prius
    Model:
    Four
    Second tank:

    508.3 miles
    Gas used: 9.404 gal
    Displayed: 56.5 mpg
    Calculated: 54.05 mpg
     
    #785 edroun, Apr 7, 2012
  6. PhysicsGuy

    PhysicsGuy Junior Member

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    Location:
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    Very first fill up:

    said 1 mile to fill up on display ;)
    487.4 miles
    Put in tank: 10.075
    Displayed: 49.6
    Calculated: 48.4
     
    #786 PhysicsGuy, Apr 9, 2012
  7. stanoz

    stanoz New Member

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    Location:
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    Vehicle:
    2012 Prius
    Model:
    Two
    Most recent fill-up in hilly Connecticut
    MFD = 56.3
    Calculated = 53.2
    MFD vs. Calculated = -3.1
    % Error = 5.77%
     
    #787 stanoz, Apr 9, 2012
  8. ChipL

    ChipL Active Member

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    I agree, love some of the ultra high mpg's that some get. If I only do my standard commute I might get 55-57... But that is not realistic in real life.

    So far very happy with the about 5% difference between the MFD and computed. Did two in a row at 51.2mpg calculated. Results and some details here: The Grey Ghost (Toyota Prius) | Fuelly
     
    #788 ChipL, Apr 10, 2012
  9. ChipL

    ChipL Active Member

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    Join us on Fuelly so we can compare notes....
     
    #789 ChipL, Apr 10, 2012
  10. kalome

    kalome Member

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    My 2011 Prius the computer readings were off by 2.2 to 2.8 mpg higher than actual.
    My 2012 Prius I just filled up (1st tank) and it is off by 2.9 mpg.
    I calculated 44.7 mpg, computer read out 47.6 mpg.

    [​IMG]
     
    #790 kalome, Apr 11, 2012
  11. alfon

    alfon Senior Member

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    Location:
    seaside, oregon
    Vehicle:
    2010 Prius
    Model:
    III
    Miles: 253.9
    gal's used: 4.779
    MPG indicated: 56.1
    MPG calculated: 53.128

    Costco reg gas with 10% Ethanol

    My wife drove about 70% of the time and
    she does not drive for mpg's.

    A month ago it would have been 46-48 mpg
    calculated.

    Temps now in the 50's with dry roads the last
    few days makes a 10% difference in mpg's.
     
    #791 alfon, Apr 13, 2012
  12. 6dogs

    6dogs New Member

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    Location:
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    Vehicle:
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    Model:
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    3rd tank
    Non Ethonal
    Miles:520
    Gallons: 9.200
    Actual: 56.5
    Computer 58.8
    This time I went past the first click of shut off & added a few more just to see how far off the computer would be. It was off but wouldn't have been off if I had shut off at 1st click about 8.9 gallons. Well that is what experiments are about. Duel foot print on this tank since DH had a crash with the Subie.
     
    #792 6dogs, Apr 14, 2012
  13. pakitt

    pakitt Senior Member

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    Last time I tanked it stopped at exactly 40L - I topped off at 40.98L. I made the calculations and the former case the error would have been 6% over 1051km (I half-filled 2 times before being able to do a complete full-up). In the latter case, it is a nice 7.48%, that is 1.48% difference...
     
    #793 pakitt, Apr 15, 2012
  14. alfon

    alfon Senior Member

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    833.2 miles (two tanks) was not reset after first fillup (424.9 miles/
    58.8 indicated / 55.849 calculated /90% highway.)


    15.631 gallons

    Indicated: 56 mpg

    Calculated: 53.304

    85 % highway 40 - 70 mph

    Reg Gas with 10% ethanol


    Tires: 195x65x15 Michelin Energy Saver
    with 44 psi in all four tires
     
    #794 alfon, Apr 22, 2012
  15. ETP

    ETP 2021 Prime(Limit),24 Venza Limit,B52-D,G,F,H

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    Ditto! No AC and 44 PSI in the 15 inch tires.

    This car seems to do better than the 2009. I am getting a 2012 in 2 weeks.
     
    #795 ETP, Apr 22, 2012
  16. Big Steve

    Big Steve ramblin wreck

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    Well I just filled up for the first time. This was on the dealer tank.

    Flashing fuel bar and only took 9.8 gal. (I had about 97 more miles of gas.)

    MID - 49.0 mpg
    Calc - 48.5 mpg
    Deviation -1.02 %

    About 35% city; temp 55-70 F; tires ~40 psi.

    Very happy, because I have been learning all week.

    SORRY: I started my own thread before seeing this, so above I cut and pasted.
     
    #796 Big Steve, Apr 22, 2012
  17. Bawb Hoss

    Bawb Hoss ...... V8 Biker ......

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    :deadhorse:

    ITS $6.60 PER GALLON HERE !!!

    :canada:
     
    #797 Bawb Hoss, Apr 23, 2012
  18. pakitt

    pakitt Senior Member

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    It is 7.86$ gallon here.... and 9.50$ in Italy (Tuscany to be precise)...
     
    #798 pakitt, Apr 24, 2012
  19. Dog Face

    Dog Face New Member

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    Location:
    CT
    Vehicle:
    2012 Prius
    Model:
    Four
    Last tank:

    524.0 miles
    Gas used: 9.118 gal
    Displayed: 61.0 mpg
    Calculated: 57.47 mpg
    Error: ~ 6%
     
    #799 Dog Face, Apr 30, 2012
  20. Dog Face

    Dog Face New Member

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    Well, my philosophy is that there's always going to be someone worse-off than you, but you still gotta complain from time to time :D

    P.S. What in the same of sweet baby jesus are those smiley faces doing to that poor animal? I didn't know you Canadians were so kinky.
     
    #800 Dog Face, Apr 30, 2012
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