i have seen form .5 to 1.0 gal more pumped than used from the car. in my BMW I can set the fuel usage and calibrate the MPG gauge in set increments, as cars will vary. I wonder if there is software to access the OBC and make corrections (this would require several fillups at the same pump) and each time a change would need to be make to correct the issue for the car. this would however be each car would have to be done so I would guess the OBC uses Air temp, engine speed, Maf input, injector cycle (the way my BMW does it) plus engine load. at this rate the car will show on avg about 1 to 2 MPG increase due to the less fuel used and I wonder if it was done that way for a reason. .5 to 1 gal is a fair amount of fuel to not be accounted for for me today I had 350miles on the tank (cold weather and lots of heat being used the last week ) I pumped 12.1 so that avg rounding up to 29MPG car displays that I used 11.3 that avg to 31 so is that how ford got the magic 41MPG for energy? I think yes