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MPG Question During Filmed Road Trip

Discussion in 'Gen 4 Prius Fuel Economy' started by JimmyPri, Sep 28, 2016.

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  1. JimmyPri

    JimmyPri Active Member

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    I recently uploaded my secound 2016 Prius road trip. This trip was to the Big Island Hawaii Volcano. If you view the video does anyone have an opinion on the mpg screens during that trip? It was aproximately a 30 mile one way trip. The return mpg numbers seem to be too high and when I add going and return mpg numbers the divide by 2 It doesn't add up to my final trip b mpg. Although the final mpg number of 70 falls in line with my overall average since I got the car. This might make more sense when you see the screens in the video


     
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  2. bisco

    bisco cookie crumbler

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    looks good to me, thanks jimmy!
     
  3. JimmyPri

    JimmyPri Active Member

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    Thank you for your comments bisco
     
  4. bisco

    bisco cookie crumbler

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    thanks for your videos, very informative!
     
  5. alanclarkeau

    alanclarkeau Senior Member

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    I think it adds up OK.

    32.4miles at 43.4MPG = .7465 gallon
    30.7miles at 192.4MPG = .1596 gallons

    Total Gallons = .9061
    Total Miles = 63.1

    63.1/.9061 = 69.7MPG - which is pretty close to your display's 70.1 (though your display on TRIP B showed 69.5miles total - did you trip them both at the same time initially?).
     
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  6. JimmyPri

    JimmyPri Active Member

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    Thanks for those calculations alanclarkeau. I Guess I was doing the wrong calculations. I was adding the 43, mpg and the 192mpg then dividing by 2 and that came to 117+ and I knew that couldn't be right. As you see I am not heavy into the numbers,but I try to help people by sharing the P
    Thanks for those calculations alanclarkeau. I Guess I was doing the wrong calculations. I was adding the 43, mpg and the 192mpg then dividing by 2 and that came to 117+ and I knew that couldn't be right. As you see I am not heavy into the numbers, but I try to help people by sharing the Prius screens.
     
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  7. alanclarkeau

    alanclarkeau Senior Member

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    I remember being told when working with statistics (which I didn't enjoy) was that you cannot average an average, as it won't give the desired answer, unless the variable is the figure you want to compare. We were told that we generally needed to go back to raw data from before it had been averaged.

    I'm not a mathematician and have just fried my brain thinking about it - but my guess is that with trying to average MPGs, the variable is the Miles, whereas the Gallons is always ONE (ie "x" Miles to 1 gallon) - so the problem with thinking MPG is that the variable (MILES) isn't what you're interested in, but the NUMBER OF GALLONS YOU $PENT YOUR HARD EARNED DOLLAR$ ON. And what happens is that the BIGGER number means that you USED LESS - not entirely logical!!

    IN CONTRAST, in metric countries where we measure in litres per 100km, the variable is the number of litres - which is the operative variable we want to $$PAY FOR$$, and the FIXED is the distance - always 100km. So, the less fuel you use, the smaller the figure. And, as far as I can ascertain, the averages in l/100km actually can be averaged. I reworked your figures roughly in l/100km and you used 5.42l/100km going up, 1.22l/100km coming down, which, when averaged = 3.32l/100 - which converts to approx 71MPG.
     
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  8. JimmyPri

    JimmyPri Active Member

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    Thanks again for educating us.
     
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  9. 'LectroFuel

    'LectroFuel Senior Member

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    Thanks for the good video! I leave the mpg numbers for the car to calculate!
     
  10. JimmyPri

    JimmyPri Active Member

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    Thanks for your comment LectroFuel. I think I am at that point now too where I just let the car do the calculating.