I have had a very steady average of 37 for months. This last fill, I went easy on the pedal, used cruise control whenever possible and stayed in manual. I increased my mpgs to 40.78. (I know one tank doesn't tell the whole story)
I calculate by the following method:
Zero the trip. Fill. Drive. Fill again. Note the number of miles on the trip and divide by the number of gallons purchased. That gives you mpgs for one fill. Repeat.
This method is accurate and you can fill at any point (ie 1/2 empty). The smart's gas gauge is not accurate enough to calculate miles per gallon.
I don't have the luxury of filling myself (Oregon Nanny Law), so I go to the same station, same pump and never let them top it off.
Happy driving!
