Well, 800 hp is up there in NASCAR territory, only with a big block. Those guys get about 4 mpg at 180 mph, but in a much more aerodynamic body and with ALL the best flow bench testing, carb tweeking, thermal coatings, etc. I'd be surprised if it made it to 10 mpg - I'd expect about 7. But like Carl said - if he has to ask the question, why is he buying it anyway? At $9.50/gallon, it should be toy. Mine's a toy (well, will be) at $3.75/gallon. That's why I have the UAV.