Im not convinced they are detuned. AC motors just aren't cable of very high outputs at very low rpm, in the same way that brushed DC motors are.
Also remember that Power is Torque x RPM. At very low RPM you might have 106lb fts of torque but not very much power.
I'm an EE, but electric motors really aren't my thing and I struggle to get my head around all the ins and outs of the various configurations...not to mention the nomenclature, which seems confusing and sometimes inaccurate. But my (admittedly incomplete) understanding is that an "AC" motor is intended to run on a fixed line frequency (60Hz here in the States, 50Hz in Japan, etc.) and at a fixed voltage (115VAC or whatever). This is the motor in your refrigerator, your washing machine, etc. It MAY use permanent magnets, but field coils are generally cheaper so are more common in this kind of motor. This motor doesn't like running on any other voltage (high or low voltages may burn it out) or any other frequency (ditto). You're right about THIS motor having very little torque at low RPM; until it winds up to full speed, it's just not operating very efficiently. There are clever controllers available which can get variable speeds out of this type of motor, but no amount of smart electronics can compensate for the motor's inherent lack of torque at low RPM.
A coil of wire with a current passing through it becomes an electromagnet. If you place it near a permanent magnet, it will attract or repel the magnet, depending on which direction the current is flowing, which determines the orientation of the magnetic field it creates. This works at any frequency, from DC (which is 0 Hz) all the way up to the frequency at which the coil of wire doesn't have enough time to build up any field, due to an electrical property referred to as its inductance. If you glue a few permanent magnets to a shaft, then place some coils around them, you can drive the coils in the right sequence to attract and repel the magnets in an alternating fashion, driving the shaft that they're attached to. To me, this configuration is a "brushless DC" motor, although I'm told that's not quite the correct terminology; it's "brushless" in the sense that brushes are not needed to energize field coils on the rotor because there ARE no field coils (permanent magnets instead); it's a "DC" motor because it works just fine all the way down to 0 RPM. This is the configuration that Zero uses, and in addition to providing full torque at zero speed, it's easy to cool the coils because they're on the outside of the motor rather than the inside.
Sorry for the rather long-winded explanation, but I find that trying to explain things to someone else usually helps my own understanding. Hopefully I didn't screw up too much in my story.
Oh, and you're right about the relationship between torque and power. In common units, horsepower equals torque (in ft-lbs) times RPM divided by 5250, if memory serves. When talking about vehicle performance, you're almost invariably going to be torque-limited at low speeds and power-limited at high speeds, with some transition speed where the torque and power limits are equal.
