I now have a little over 11,000 miles on this truck. I tow a 28ft 5ver which weighs loaded around 9K (lots of storage left yet) and I tow a fishing boat behind the 5ver which weighs around 2000 lbs. My CGVW is right around 18K with everything hooked up. When the truck was brand spanking new, towing just 5ver into a 35mph head wind on winter fuel I squeaked out 9 mpg. A month later with 5ver and boat connected I averaged close to 11 mpg. It seemed the closer I got to the magical 10,000 mile mark, the better the towing milage. The last two trips out I've averaged 13. 2 mpg. My speeds are between 60 - 70 mph. I voted 12 - 14.