A few words of explanation. The mileage you want to report is for the typical type of driving you do. If you are always on the Interstate in uncrowded conditions, then that's what the MPG you should report.
If you're stuck in stop and go traffic around town and not even coming close the the "City" mileage the EPA says your vehicle should get, then report the MPG you get.
If you turn the engine off when coasting down hills and open the door and push with your foot to help get a few more ounces out of each gallon, then report the mileage.
Your 'everday' driver (meant to be 'everyday' driver) is the one you want to report on. If, like a certain saint, you have several vehicles, pick the one that you put the most miles on in a year, not the exotic
Corvette sports vehicle that only gets driven around the block when there is no precip within 250 miles.
Just kidding Bob.