I was wondering how accurate is that average mileage per gallon display. I've noticed it's not very accurate on my 2001 EB. Wondering what peoples thought were on that average mileage display.

 

I have two BMW's and there average for the computer is with in a tenth of a point when done manually. As for my Expy, I calculated it one time on a trip manually and it to was within a tenth of a MPH. Might be luck but it seems right on. Plus I always do "in my head" calculations on trips for how large the gas tank it and it seems right on the money.