Originally Posted by MalcolmB
I'm not sure how I could do a similar calculation using power alone, since power is zero at zero rpm, isn't it?
Power = RPM * Torque, so yes indeed.
As I see it, and since my background is mainly from electricity, I tend to see it as torque is related to current and rpm is related to voltage. Both torque and rpm are potentially very powerful, but rpm without load or torque without movement won't make anyone happy, current without voltage or voltage without current are equally pointless. Of course.
At that perfect time zero when you slam the throttle there's no movement and thus no rpm and thus there can't be any power released and no actual work is done. There's nothing but torque and that torque will force the car to move by simply overcome friction and in THAT very instant, when the car starts to move, there's rpm and therefore you get power! If you don't have the torque you can never overcome the friction and if there's no rpm there's no movement.
Now, power = rpm * torque, if we apply that to the wheel the ONLY thing that regulate the final power at a certain speed of the car is torque! Nothing else. The rpm is directly related to the speed of the vehicle (decided by the size of the wheels) and there's nothing you can do to change that (except by changing speed or tires, of course) so if you want to alter the power that propel the car you alter torque. That's how all cars work.
CroDriver mentioned that Formula 1 cars have engines that only have half the torque of his BMW. That might be true, but that's missing the fact that a Formula 1 car is very aerodynamic and can rev to up to 18000 rpm, thus it doesn't need as much power as the BMW to gain speed and there's a lot of potential power in the high top rpm. However, those 18000 rpm can't be applied to the tires directly so they have to be geared down, trading rpm for, yep, torque and therefore better acceleration.
So my personal view is that torque is the main key here. For an EV acceleration is all about how much motor current you can keep up (which is why the Zilla 2K is still unbeaten on the drag racing track as far as I know), the motor current turns to torque which then is transformed to acceleration. The gear ratio has to be optimized for maximum continumous torque without hitting the limits (max rpm, max motor voltage etc), a motor with less torque but higher rpm can be geared down to trade all those rpms to torque, but torque is, in the end, what accelerates cars.