Elon's tweet today said of the dual motor Model 3: "AC induction front & switched reluctance, partial permanent magnet rear. Silicon Carbide inverters in both. Performance drive units are lot sorted for highest sigma output & get double the burn-in." The silicon carbide part refers to the power electronics in the inverters, like transistors and IGBTs. If you use Silicon Carbide instead of Silicon as the base wafer, you get 10x voltage capability with the same thickness material, less heat loss, more efficiency, etc. More info here: https://spectrum.ieee.org/semiconductors/materials/silicon-carbide-smaller-faster-tougher
Couple comments on the article. None of the drive electronics I am aware use a boost stage. That is the reason for high voltage battery packs. No need to take an extra efficiency hit. Also, smart drive controls can use synchronous switching to minimize loss through diodes. The downside is the need for high speed current sensing (although that can be mitigated via less optimal synchronous timing and partial use of diodes). In a continuous conduction mode state, the diodes only handle the short dead time between top and bottom switching. Of course, less loss is always better, but the main switch loss is the bulk of the power dissipation.
Here's a paper evaluating SiC MOSFET's in auto inverters. Here's a presentation from last year that has some market info of where SiC will be headed. Pages 6-12. It's interesting to me that the power BOM is $387 and the sense BOM is $77, total $704. As economies of scale build, it's obvious SiC will be in every EV. To me it's like the switch from carburetion -> fuel injection. Also, we know the inverters/SiC components in the M3 are likely from Infineon.
