I just made a 1700 mile round trip from Louisiana to South Carolina and back, running solo. I got a solid 18.5 mpg while running steadily around 70 mph. My diff has 3.73:1 gearing and I have a BAKLiner "rolltop" bed cover. It hides my fifth-wheel hitch. When towing, I get anywhere from 9 to 12.5 mpg, depending on how big a hurry I'm in, and whether I'm headed TO the Rockies or FROM the Rockies.
