4x4ord wrote:
400 HP is a little bit skimpy for larger RV's. You need over 500 HP to pull a large RV (20,000 lb fiver) up a 6% grade at 65 mph. I haven't been in the mountains with my 2021 Ford but my 2017 with 440 HP pulled down to about 50 mph on some hills with a 17k lb trailer in tow.
Probably more of a gearing issue. If it can't get the right combination of RPM and torque, it won't reach max HP.
Very rarely does any engine hit it's peak HP rating in terms of real output.
But still doesn't conflict with the statement that 95% of the time, you can pick your speed. Also you are probably flying by the trucks in the right lane at 50mph.