Changing your door lock setting doesn't require the infotainment system, the GUI for it currently does. That's vitally important to understand. The systems are

Changing your door lock setting doesn't require the infotainment system, the GUI for it currently does. That's vitally important to understand. The systems are mingled but they don't have to be and in fact shouldn't be. Also, not all isolation is the same. Consider the scope of isolation between multiple sandboxed apps (some accessing the raw internet) on a single computer and two separate computers connected via a specialized protocol-aware data diode.