Originally Posted by fanoftheliving
Is that calculated or based on the average readout on the dashboard? The reason I ask is that my car is incredibly inaccurate. On my last all highway trip the average MPG was reporting 40.2, but hand calculated came out to 35.8 - which is nowhere close. My experience has been that the average MPG readout is inaccurate.
You need to reset the meter in the car occasionally, I usually do it on every tank. Fuelly calculates the same as you would by hand and I would imagine weighs those averages based on gallons consumed and miles traveled, so a 400 mile trip based average would count something like 4 times more than if you filled up after only 100 miles.
That is just my guess. I also think I read Fuelly bases it's number on only the last ten fill ups, but I am not positive about that. I'll look at the FAQ later.