On August 28, 2015, I tested my highway mileage on perfectly flat roads in Nevada at various speeds: I got 18 miles per gallon at 60 mph fully loaded with my camper, with tires inflated to 45 psi; 17 mpg at 65 mph; 16 mpg at 70 mph; and 15 mpg at 75 mpg. Not bad, considering the truck without...