Went on a two week 2,500+mile trip with a 36' 8,000 pound TT. 8 states, Great Smokey Mountains, Appalachians and tons of other stops. Cummins pulled with absolutely no effort. Averaged 13mpg overall with speeds up to 80mph. Some serious mountain passes and I was passing everything on the way up. Exhaust brake on the way down. Heavy rains and winds were no problem. Love this truck!