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Thread: MPG gauge accuracy

  1. #1
    Member azdonw's Avatar
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    MPG gauge accuracy

    This has been discussed a few times in these forums, including my post here https://mirageforum.com/forum/showth...rip-MPG-report
    Since that thread, I've been keeping records by resetting my MPG-B meter every time I filled up, so here is some real world data. A minus (-) means an optimistic measurement. Plus (+) means pessimistic.

    MPG-B difference from calculated (in MPG)
    -2.1
    -1.1
    -.15
    -4.2
    +1.9
    -.20
    -1.0
    Summing, and dividing by 7 equals -0.98
    So I will assume my meter is approximately one MPG optimistic.



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    Moderator inuvik's Avatar
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    Quote Originally Posted by azdonw View Post
    This has been discussed a few times in these forums, including my post here https://mirageforum.com/forum/showth...rip-MPG-report
    Since that thread, I've been keeping records by resetting my MPG-B meter every time I filled up, so here is some real world data. A minus (-) means an optimistic measurement. Plus (+) means pessimistic.

    MPG-B difference from calculated (in MPG)
    -2.1
    -1.1
    -.15
    -4.2
    +1.9
    -.20
    -1.0
    Summing, and dividing by 7 equals -0.98
    So I will assume my meter is approximately one MPG optimistic.
    That’s pretty close to my observation of almost 60,000 miles of fuel tracking. I also reset my “B” at every fill. It averages about 1.0-1.5 over the actual.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.5 mpg (US) ... 17.2 km/L ... 5.8 L/100 km ... 48.6 mpg (Imp)


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    I seem to average about .7-.9 higher than my calculator says I get, 1mpg off average isn't bad for a calculation!
    2018 mirage ES manual

        __________________________________________

        click to view fuel log View my fuel log 2018 Mirage Es 1.2 manual: 41.6 mpg (US) ... 17.7 km/L ... 5.7 L/100 km ... 50.0 mpg (Imp)


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    Senior Member DonkeyPal's Avatar
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    I wouldn't really expect a this sort of MPG gauge to be especially accurate. I wouldn't expect it to be as accurate as others in this thread are saying it is. If that is so, it may be pretty good for what it is.

    I think the purpose of a gauge like this is to help drivers develop better driving habits. And the only real way to know what mileage one is actually getting is to calculate it based on miles traveled between one fill-up and the next.

    That being said, since we have been driving around with the gas that was in the 2015 Mirage DE we bought last Wednesday, and didn't fill up the tank for the first time until today, I won't be able to calculate mileage until I fill up again. We took a 100-mile joy ride today, and watched the mpg gauge just to see how well it thought we were doing. It got up to 46.5 by the end of our trip. Even if it's not precise, it sounds pretty good.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 automatic: 43.0 mpg (US) ... 18.3 km/L ... 5.5 L/100 km ... 51.7 mpg (Imp)


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    Hubcap Enthusiast Scratchpaddy's Avatar
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    Quote Originally Posted by DonkeyPal View Post
    I wouldn't really expect a this sort of MPG gauge to be especially accurate. I wouldn't expect it to be as accurate as others in this thread are saying it is. If that is so, it may be pretty good for what it is.
    All the GM cars I've had with MPG readouts were optimistic by 10% or more. It was a disappointing reality check when it came time to fill up, every time. I've heard similar things about other cars, too. They're just about all optimistic, and most drivers don't bother verifying with the trip meter and gas receipts.

    So, from the results here, the Mirage gauge is pretty darn close.

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    Moderator Eggman's Avatar
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    I've found it is about +2.2 mpg optimistic.

    I've been comparing the MID B and actual at every fill up and averaging along the way. Details can be found in my forum Fuel Economy Log.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


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    Quote Originally Posted by Scratchpaddy View Post
    All the GM cars I've had with MPG readouts were optimistic by 10% or more. It was a disappointing reality check when it came time to fill up, every time. I've heard similar things about other cars, too. They're just about all optimistic, and most drivers don't bother verifying with the trip meter and gas receipts.

    So, from the results here, the Mirage gauge is pretty darn close.
    My Micra is 15%! optimistic. It sucks.

    45mpg is actually 38. Normally it says 6.2l and I get 7.3. Haha.

    Mirage is much closer. 4.4 is normally 4.5 or 4.6.

        __________________________________________

        click to view fuel log View my fuel log 2018 Mirage ES 1.2 manual: 43.5 mpg (US) ... 18.5 km/L ... 5.4 L/100 km ... 52.2 mpg (Imp)


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    I agree too.

    There is very little difference between calculated and actual consumption.



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