I have a 2006 Mega Cab dualie. 4 WD It gets 16-18 highway and once keeping the speed below 65, I squeaked out 20. Around town 13. With a 28 foot trailer loaded on the highway 10. Pulls like it has no load behind it. My 97 4x4 ext. cab would get 22-23 highway,17 in town. Towing with a 24 foot trailer on highway 15. Only problem was it was a dog on hills. It was stock.