You can get a PhD in gulag tech cars, or you can get a pre-gulag tech (i.e. old) car.

But they're going to argue that custom firmware is bad "for safety". And they're not necessarily wrong, especially if they deliberately make an entangled mess where safety-critical control systems share code paths with their spyware.

I agree that this is one area, where going low tech is a good choice. You aren't loosing any important functionality.