Yes, that document makes excellent reading for anyone with a heavy vehicle.
All the HP requirements in the document are AT THE REAR WHEELS, so engine HP must be quite a lot more because of loss to cooling fan, alternator, transmission loss, rear axle loss, etc.
Note especially the HUGE difference in HP required to move a heavy vehicle up a grade compared with the small increase in HP needed by a car.
It also give an excellent perspective on how few MPH more you will get from those 30-50 HP increase devices (like 5 MPH those few times you are on those 6% grades).