Why power/weight and not torque/weight?

[gregwatson]

OK. So Torque accelerates. And obviously weight is a factor. So how come we use power/weight ratio as an indication of a car's ability to accelerate, and not the torque/weight ratio??

[gregwatson]

So if you have two vehicles, same weight, same power but one has higher torque than the other, which will accelerate more quickly?

[gregwatson]

OK..

I was hoping to finally get an intuitive understanding of this but I don't think you can. You can get an intuitive feeling for what torque is "ie twisting force" but when you start talking about power then you need to start including things like engine speed, and gearing, which makes it harder to grasp without thinking about it.

The only way it makes sense to me is:

Torque is the thing that accelerates the car. Power is the ability to stay in one particular gear for longer (ie the ability to apply that torque at higher revs). With high torque but low power, the torque would drop off rapidly as the revs rise, so you have to change gear (and therefore use worse gearing). With high power, adequate torque is still available at higher revs so you don't have to change up for longer, hence you are using the lowest gear ratio for longer..

I think that kind of makes sense to me..???