It's accurate enough. It takes into account every bit of time the engine's running - including all that idling at stoplights, etc. That said, my MPG is usually off by 1.5-3 MPG most tanks (2012 model year)
If you do an all-highway trip, you'll see MPH in the 50's-70's depending how traffic was.
If you do an all-highway trip, you'll see MPH in the 50's-70's depending how traffic was.
