I’ve reached the limit of my personal experiences that I will be sharing.
But, if you don’t know anyone in the offensive security space and still want to get some general feelings, perhaps you can start by looking into things like “Tesla CAN bus security,” “Tesla infotainment security,” and “Tesla NFC fob security.”
Plus, here’s a heuristic for why they would have horrible security: they a are poorly built product which focuses more on flash than substance made by a company with an owner that is known to cut corners, and security is absolutely not one of the key selling points of this(or any other) car.