I usually just fill my cars up and drive not really paying attention to my mileage other than what the OBC says.
On my last fill up I reset my trip meter after remembering this thread.
I can't believe it
I filled up with 92 octane Non Oxy 0% Ethanol on my last fill up.
24.xx gallons
292mi. before empty with 7mi. range left according to OBC

NOT COOL