What ever motor you go with, if it is gas powered. Try to put a hydrogen reactor on it. A friend of mine built one for his toyota p/u (4 cyl) and went from 18 mpg to 39 mpg. the hp gain was unreal. When he turns it on when he gets up to speed (55) he has to let off the gas a little. He also put one on his 1 ton plow truck w/ bbc. It increased mpg from 9 to 41. Lastly, go airodnamic, if you feel ambishis. Cut 1 foot out ofthe back and 2 feet out of the front.