Are MPG ratings much less accurate then they used to be?

Discussion in 'General Motoring' started by General Schvantzkoph, Jul 18, 2005.

  1. General Schvantzkoph

    gary Guest

    I thought the ratings were done on a flat road on the moon where there is
    1/7th the gravity in order to get those MPG results.

    I never thought they were very accurate, I only use them to compare one
    vehicle with another to get a relative ranking when I do a vehicle purchase.
    gary, Jul 24, 2005
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  2. General Schvantzkoph

    gary Guest

    I remember way back when I used to do my own tune up, timing and all. Now I
    don't even recognize what is under the hood.
    gary, Jul 24, 2005
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  3. General Schvantzkoph

    Matt Whiting Guest

    It depends on your driving conditions. Every vehicle I've owned in the
    last 20 years has obtained within 10% of the EPA ratings. I drive a mix
    of highway and city, but mostly highway (80%). I tend to get very close
    to the EPA highway ratings and almost never get anywhere near the lower
    city ratings.

    Matt Whiting, Jul 24, 2005
  4. The difficulty is in the stackup of assumptions and calculation margins.
    The MPG protocol, believe it or don't, amounts more or less to "Let's see,
    we measured *about* such-and-such percent HC and CO in the exhaust, and
    the catalytic converter efficiency is *about* such-and-such percent, so we
    can assume that *about* such-and-such amount of CO and HC is coming off
    the manifold, which would mean that *about* such-and-such an amount of
    fuel was burned".

    Never mind that simply measuring the liquid volume of fuel before and
    after the vehicle is run is considerably easier, more direct, more precise
    and more accurate, that's not how it's done.
    Daniel J. Stern, Jul 24, 2005
  5. General Schvantzkoph

    tim bur Guest

    they are not far off problem is people do not go the 55 mph the calulations
    were done at
    they still use the old standard of 55mph being the national speed limit and one
    i feel we need to go bac to so gas starts to stack up at the refineries and
    watch how fast the price comes down
    tim bur, Jul 24, 2005
  6. General Schvantzkoph

    gary Guest

    "I can't drive ... 55"


    gary, Jul 24, 2005
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