If you doubt Tesla's engineering then you need to watch this
(www.youtube.com)
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What impresses me is the Tesla motor parts can turn at 18000 rpm and not explode. A Dremel tool spins its head at ultrasonic frequency max (20K) but it is small and light. For the Tesla motor to spin at that speed is strong parts engineering, because 1) it doesn't explode 2) wear at that speed is high normally. I have to wonder how they lube it, unless they use magnetic non-contact bearings.
Another impressive thing is the robotic manufacturing that Musk set up - it is very efficient. Others use robots but he has polished it all.
Average cheap angle grinder can turn at 12000 rpm and not explode. Turbochargers in car engines rotates at 100000-200000 rpm and don't explode too. Nothing exceptional in 18000 rpm for electric motors really.
Lubrication is not a problem too, look how turbochargers lubricated, f.e. And at 18000 RPM you could just use ball bearings.
High RPM is mostly a question of rotor balance. Today, with modern sensors you could balance any rotating part pretty well.
Because the radial force is proportional to the square of the velocity, there is giant difference between the force on materials at 12K and 18K spin speed. Any casting or machined metal in the Tesla would have to be flawless internally.
As for turbochargers, gas vehicles have oil pumps to supply lubricant to everything needing it, an electric car doesn't. At 18K, ball bearings would need forced lubrication, as the centrifugal force would strip them of lube very soon. At Garrett Airesearch we had to run a high speed rotor in a vacuum with magnetic bearings because a metal one could not last at these high speeds. That is why I'm impressed with the Tesla motor design.
Only rotor. And that is not that hard.
Or you should use sealed ball bearings. Also, centrifugal force for bearing much less that for the rotor, since diameter of rotating parts is much smaller. Vaccum cleaner turbines runs at 20-30K RPM, and ball bearings perfecly OK without forced lubrication for many years. SKF gives limiting speed for randomly taken W628/8-2Z bearing at 45K RPM f.e.
I had the wrong model. I was envisioning the rotor running in a planetary outer bearing race but with the hub connected to the wheel. But that's wrong because it couldn't be direct drive, the wheel does not turn at 18K rpm of course. I'm going to have to go research the per-wheel drive train.