How much thermal energy can you get out of a gallon of gasoline, and if all that energy could be transferred to the wheels how far could your car ideally go if the total force of friction it worked against at constant velocity was 2,200 Newtons

One gallon of gasoline can produce 114,100 btu of heat. Multiply that by 1055 J/btu to get the energy in Joules. That would be 1.204*10^5 J.

Setting that equal to (friction force x distance) results in a distance travelled of 54,716 m or 54.7 km/gallon (34.0 mpg)

Some cars can do better than that despite the fact that only about 40% max of the heat energy can be converted to work, because of the second law of thermodynamics. Such cars, like the Prius, have lower friction and a braking energy recovery system.