One more thing to think about, on this line of questioning, is efficiency in "normal" driving situations.
If you're driving in a straight line, with good traction on all wheels, will a single larger motor be more efficient than two smaller ones on each wheel? For many people, I think that's 99% of their driving, so it makes sense to optimize. Especially on electric vehicles, where increasing battery capacity is much harder than just adding an extra gas can.
Maybe in that case the complexity of AWD/4WD/Traction control makes sense in that case.
One motor per wheel, in the wheel, is an old idea. It's been used most notably on LeTourneau heavy equipment. The usual problem is too much unspring weight, not a problem for giant earthmovers but bad for fast cars.
Michelin was pushing it for cars, with their "Active Wheel" concept, from about 2003 to 2012.[1] That seems to have disappeared. Siemens has demoed a motor-in-wheel unit, and Volvo and Nissan have fooled around with this. Protean, in Shanghai, is trying to sell their wheel motor. There are others. Nobody has shipped production cars yet, though.
"One motor per wheel, in the wheel, is an old idea. It's been used most notably on LeTourneau heavy equipment. The usual problem is too much unspring weight, not a problem for giant earthmovers but bad for fast cars."
hmmm ... I wasn't thinking about motors in the wheel, although I am familiar with that concept.
I was thinking about a more pedestrian motor per wheel configuration wherein the motor is just behind the spring ... and is thus, sprung weight ... is there even space for that ?
If you're driving in a straight line, with good traction on all wheels, will a single larger motor be more efficient than two smaller ones on each wheel? For many people, I think that's 99% of their driving, so it makes sense to optimize. Especially on electric vehicles, where increasing battery capacity is much harder than just adding an extra gas can.
Maybe in that case the complexity of AWD/4WD/Traction control makes sense in that case.