look around for a f250 or 350 with the 7.3 powerstroke. for 2 reasons; 500miles per tank(bout 20-25mpg) and no matter how much you lift it mpg wont change much. i picked 99 350 4dr longbed up for 9,000 out the door total. 250k on the clock. just my 75 cents. oh and i make my own bio fuel for that much.
Post your wanted ad in the classifieds , also your mpg is abit optimistic.