I suspect that the motors are not the principal limitation on regen. The maximum regen on my Tesla S 70D is 50 kW whereas the total motor power is about 250 kW

I suspect that the motors are not the principal limitation on regen. The maximum regen on my Tesla S 70D is 50 kW whereas the total motor power is about 250 kW. I suspect it has more to do with the control system and the current capacity of components in the inverter.