Who has measured their MPG's on their own to see if the on board MPG measurement is correct?

 

Last night when I filled up the display said 33.1 mpg but when I figured it up it was 29.6 mpg.



It is always high by at least a couple mpg. I think there is a differnce between models as far as accuracy. I know my speedo reads 2 mph fast.

 

I use Fuel log to compare the onboard and(at least for me) its close. within ~.5 mpg

 

I find mine runs a little low (2-3mpg most of the time).