Audi e-tron Quattro and Sportback: New Tech Details on the Tesla Model X Rival Interesting that Audi is claiming development of a current-excited synchronous motor for its new EV. As opposed to an induction motor, current must be supplied to the rotor windings on this type of motor -- perhaps by slip rings, though it's possible to do it without contact. They seem to be looking for the lower losses at very low loads that Tesla gets with its induction motors on the S and X, but with more efficiency at higher power levels. I still believe Porsche is going the PMAC route, but it's possible I'm wrong on that. One thing is clear: it's going to be years before motor and controller design fully stabilize and everyone understands exactly what the best solution is.