I read your article several times. And I agree totally
with you on your carefully laid out explanation and calculation.
My post is not against your idea that it is the Power that determines the drive force.
Actually, my point is that the distribution (or shape) of the torque is also a very important factor to a vehicle's peformance.
May be the better way (to me) to show the engine performance is a graph with
X -- vehicle Speed
Y -- Drive Force (power/speed)
on this graph there will be multiple lines and each belong to a gear selected (first gear, second gear..)