I’ve never worked on a Tesla. I’ve left the trade long ago finding my way in software engineering instead.

Tesla is probably the only one I’d trust though. While I don’t expect them to be bulletproof either (at least not at first), I expect them to quickly catch on should this kind of theft appear, and make the necessary fixes. In any case I doubt they’d be stupid enough to accept arbitrary code over a diagnostics port (if they have one even). I mean, even if we forget security, why would they? Teslas update remotely via the Internet.