SO, you DID stop for gas? How many times? Did you start with a full tank, then stop and refuel? Assuming a 30 gallon tank, and 989 miles (Philly-Orlando), that works out to an impressive 16mpg if you started with a full tank, and refueled once. But, that is not the same thing as doing that trip on ONE tank, which was the original statement if I read right, and would then require you to get 32mpg (or for you to have dual tanks and about 60 gallons)