Copper or Aluminum, and Iron, are all you need to make a motor (and an insulator like lacquer or ceramics).
Yes, you can build lighter/more efficient motors from permanent magnets, but that efficiency only holds at lower RPMs. Higher RPMs and permanent magnet brushless motors begin to suffer from Eddy current losses in the large monolithic magnets that make up the armateur of the motor. Their efficieny begins to drop as their speed increases and the drive power frequency increases.
Induction motors have much more leeway in terms of high speed operation... they require only good design principles for the stator and armateur, and metals that aren’t too special in nature. Induction motors are also more reselient to overheating. If you don’t put enough heat into the stator to melt the insulation on the windings, you can keep pushing power into them. Permanent magnet motors will begin to have their permanent magnets degrade in strength.
On the other hand, I thought there was a push to start mining rare-earths from the ocean. Anyone know what came of this?
Personally, if I was a car company not in China’s special graces, I’d focus on induction motors. Until more precious metals supplies come online, precious metals are going to be pricey.
Induction motors require AC current, which is kind of nonsensical to create from DC batteries in electric cars.
Most DC-to-AC converters produce square waves that don’t play well with induction motors, and pure sine wave DC-to-AC converters are inefficient.
Thank you for your expertise! Would it be practical to build a linear motor such that half the motor is in the road bed and the lighter half would be on the bottom on the car? Possibly any car could be turned into a hybrid by mounting a permanent magnet on the bottom then have the road bed pull the car along magnetically. Another option is pass electric power from the road bed to the car inductively. That way the car doesn't need a 700 lb. battery on board for power. It could use its conventional motor when not on a high volume specially equipped highway. If the future is electric cars we're going to have to build more power distribution, so why not built it right into the road bed?