Cyberpunk

That seems consistent with your opinion on the OS but I'm not sure it's consistent with your opinion on public safety. People currently rebuild engines from junk, they replace their own brakes, convert their cars to run on different fuel sources. I would feel that tinkering with firmware poses, at worse, a similar risk. It doesn't strike me as especially new or threatening. How do you feel about the right to repair?

Do you draw the line at creating something new? Because with hobby cars, they build them from kits or gather parts from a bunch of junkyards and reassemble them into working, often customized machines. No dealership or assembly line involved. And it is not uncommon to build sleeper cars by swapping in an engine the car was never meant to have. This can involve modifying the frame and rearranging other components to accommodate it. I'm not sure where the line for making their own engine is - is it a new configuration of existing components or do you mean like milling a new engine block? Either one has software analogies.

I've been skeptical of cars having OSs advanced enough to need updates, and I'd personally air gap them from both the Internet and the onboard entertainment system. But a glitchy OS doesn't strike me as being far worse than the stuff I mentioned above done badly. States might have to figure out how to inspect them the way they do with the rest of the car (in states that actually do vehicle inspections at least).