Just got back from a month in Florida. Around 3,400 miles towing, 4,000 total. Trailer weight was around 9-9,500 depending on how much fresh water I was carrying (holds 80 gal). Truck never lacks power and usually will tow in 5th gear, downshifts to 4th on hills, seldom hits 3rd gear. Not exactly climbing the Rockies I know but did hit some hills. Towing average mpg was 9.2 at 64 mph, unloaded it will get 18-19 mpg at 65 mph if ideal conditions. Pretty darn good for a 2500 truck with 4:10 gears. It is a Big Horn model pretty well loaded, payload is 2975 lbs, GVW 10,000 lbs.