If you are tracking your mileage using the trip meter in your car, you may find you are being short changed, on average by about 5%. If you have a GPS, do a quick check yourself, work out the difference by driving at 60mph on your GPS and compare against the speedometer in your car. Typically when doing 60mph on the GPS you will only be doing about 57mph on your speedo. So, if using the speedo to track your fuel usage, you will actually be travelling 5% more than you are tracking, making your fuel economy appear worse than it actually is.
by bearmeister on December 24 2009
this tip works for 50% of voting Fuelly members.