I just got back from my first trip towing about a 6500# toy hauler from Sacramento, Cal. to So. Cal. and back,about 1200 miles total. I only could manage to get 10mpg at the best, and the worst was 8mpg. I usually get 13.5mpg unloaded with 80% hwy and 20% city driving, and I am not to happy with that either. I wanted to make this first trip before I made a decision to take the truck to the dealer. I have 12,000 miles on the truck and the fuel filter was changed @ 8,000. On my trip I had the cruise set @ 65mph , I know that you will get low mpg's with that speed, but not 8mpg!!! Has anybody else had this problem? Other than the mpg's, the truck towed great, and no overheating (knock on wood).