I don't think the motor conditioning would make much difference. The issue is with the rotor, which is constantly cooled as long as the car is moving. If you don't cool the rotor, it will overheat, even with mild loads. Assuming a 10 kW power consumption, probably around 500W will be generated in the rotor. The rotor doesn't have much mass so the temperature climbs quite rapidly. If you're going to precondition the motor while driving, you need to work against the heat being generated, and that is probably difficult. You can't put the cooling exactly where the heat is being generated, you're stuck with only cooling inside the drive shaft, so you end up with a temperature gradient from where the heat is being generated to the drive shaft. Of course, cooling the drive shaft more will lower the max temperature somewhat, but it should mostly just work to increase the slope of the temperature gradient. In conclusion, I think you will see some improvement, but not very much. A few additional seconds at max power maybe.