Average MPG on trip computer

[Black 535i]

...I believe that the onboard computer figures out averages and you are figuring out the 'actual' average as I do. I too am way off the onboard computer averages everytime. It takes into account how you drive, how you accellerate and all that whereas we just figure out the average of mileage divided by gallons used and not how they are used. Anyone else have a theory on this?

[billy]

if you select mpg on the OBC, you should notice that the average will reset every time you press s/r button, therefore you would just start getting the mpg average from now onwards rather as say the last 100 miles