I am a retired Engineer also and designed engines. You can not argue with the equations above. they work for both gas and diesel,in fact any engine.
Let's keep it simple!! Go to any NASCAR race or drag strip. See that they are talking about weight/HP not torque to make there machines do something faster.
It also works for Motoehomes!!!
The purpose of a race car is to go fast. Horsepower is more important than torque as the car is relatively light and needs to possess violent acceleration and high top speeds. The discussion of this thread is to get a heavy motorhome up a mountain; horsepower is less important than torque. It is not the same desired results as what is needed in a race car. 40,000 pounds of MH towing a 3800 pound car behind up six percent grades that are miles and miles long. It is not the same thing. And what does the Holiday Inn reference mean?