So you got about 3 miles per gallon.
Very possible, depending on more factors than I have time to list, and you even care about reading. If you want to increase your mileage, take the radiator cap off and drive a Prius under it. Instant 56 miles per gallon!
Not trying to be a jerk, but you have told us squat. We dont even know what engine you have. I have a 5.2lt, with air on and cruise, I can coax 18.5 to 19.5 mpg. I stick my foot in it, I can get less than 8.
Your Mileage May Vary