First of all, let me apologize if this is an oft repeated topic.

I have owned a 2009 AT Fit Sport for about three weeks. During this time, my mileage gauge in the instrument panel has registered an average MPG anywhere from 36.5 to 42 mpg, for a given tank...the variation being accounted for by city vs. highway driving. Now, as I am a bit OCD, I have also been keeping track of the MPG per tank on my own using the standard Odometer method. My MPG per tank has been consistently lower (by usually 5 MPG) than the "average" on the display.

Now I realize that this is a Fit (an economy car), and the logarithm(s) used in the little computer to calculate MPG is probably not complex nor sophisticated and therefore not entirely accurate, and is probably based on loose and varied readings from a limited number of sources. But 5 MPG is a good bit, I think.

Does anyone have any idea how the "computer" calculates MPG for the Fit? My wife's Mini Cooper does the same thing, yet is quite a bit more accurate, the over/under being under 2 MPG per tank. More importantly, it is quite a bit more appropriate to say "over/under" in the case of the Cooper, as its computer is off at different times both over and under the Odometer MPG figures. My Fit is only registering far higher MPG figures.

Minor complaint, to be sure. But curious.

 

You might want to do a search on "MPG Gauge" or something like that, because this topic has been discussed numerous times. And, yes, the guage is always on the high side, and 5 mpg off isn't uncommon.