I own a 2013 duramax pulling an 11,000 lb Cougar 36 foot fifthwheel. I live on the East coast. We visit the East Coast Beaches all the down into Florida. I maintain a speed of 60-65 mph. For sure, the Duramax/Allison transmission is a super combo. Plenty of power when its needed. Driving sensible, I get 12.5-13.2 mpg. Running truck without Camper I get 21-22 mpg on interstate, but if I run 70mph, the mileage drops to 19-20mpg. Thats still great for me. Yes I really would buy another one if I needed too.