In first place let's frankly say that interconnecting entertainment system with anything that affects safety is dump idea. They top-notch security professionals

In first place let's frankly say that interconnecting entertainment system with anything that affects safety is dump idea. They top-notch security professionals should know that. I was developing entertainment system for Volkswagen's cars a while ago. At the time their cars have several networks interconnected with a simple firewall. They were separated into domains, if I remember correctly it was core (engine, steering wheel), first level (reporting, airbags, etc.), second level (opening windows, etc.), and then entertainment system. The firewall was one-way. Systems on lower level are able to intercept some messages from higher levels, but are unable to send anything to higher level (with some exception between core and first level). That also means that the entertainment system is unable to open/close windows for example - you have physical buttons for that. It was a while ago and my memory is rusty. But you get the idea that car systems can be build securely with competent engineers.