I've never drive. In Europe but here in western Canada we have some hills and it takes power to pull 100,000 lbs up even a 4% grade at 60 mph and it doesn't matter what you are pulling with. When the grades are very short the momentum of the truck can carry it along way up a hill but on a long 4% grade you will never find a 100,000 lb truck going along at 60 mph.....unless it has over 800 ponies under its hood. Many trucks on the highway around here are pulling far more than 100,000 lbs as well. For a truck and Rv 400 HP seems to work quite well but it really isn't over kill. If you want to maintain 60 mph in the hills a little more than 400 hp is needed for many RVs.
