I'm thinking of motorhomes. My 9500 pound, 27' 1990 E350 (Class C) motorhome with 460 V8 got barely 8 mpg. Then I bought a 13000 pound '97 Class A 32' on a Ford F53 chassis and the 460 V8 got only 7 mpg. Now I am back to a Class C, a 2000 28' with the 454. I think it weighs around 11000 pounds. Just picked it up Monday, so haven't had a run to see what the fuel mileage is, but a couple guys on a motorhome site claimed 10-11 mpg with 30+ foot motorhomes in the mountains. Kind of hard to believe.