I think you're focused on the motor, when that's the least important part of the equation. As you point out with the BMW i3, the source of the electricity is i

I think you're focused on the motor, when that's the least important part of the equation. As you point out with the BMW i3, the source of the electricity is important. In battery mode, it is actually more efficient (27 kW-hrs/100 mi) than the Model S (35 kW-hrs/100 mi), but that's obviously not true when the range extender kicks in.