Gas Mileage

Well when i use instant and am going about 30 without pressing the gas it says i get 35MPG, ok and when i use average it says like 13mpg, well this is just around town. well i have 10 gallons of gas but 13x10 equals 130 mile range and it says 93 miles left. should i try it on the highway? or is just pitiful?

I don't think it counts the last gallon or so in the tank. It considers it 'E' or 'L' at that point.

They have two gallon reserves so yea,they read two gallons shorter than they actually are.And those MPG computers arent always right either.