回复：Don't forget the function of transmission

I totally agree what you said that

"Torque at the driving wheel is NOT the same as the torque at engine shaft."

After all things considered(transmission/gearbox/differential...) the torque
at wheel is amplified. And the amplify ratio
is different for each gear (first gear, second gear...)

That's why I said this before:

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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..)
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I like my graph better because drive force is more straightforward to understand than torque. Because
that's what we really feel on our back when we drive
the car.

(more acurate, we feel drive force on wheel-resistance)

Drive Force on Wheel = Torque on Wheel/Radius of Wheel

If no other conditions changed and we just shrink the wheel size by half, we can double the drive force.
I believe you have mentioned this in your article also.