I am less concerned that it's possible to exploit the entertainment system from a phone, and far more worried that the it's possible to exploit the security-cri

I am less concerned that it's possible to exploit the entertainment system from a phone, and far more worried that the it's possible to exploit the security-critical subsystems from the entertainment system. I realize that the screen is part of the entertainment system and it sometimes needs to display information about the car functioning, so it needs to have read access to very critical systems. But is there any reason for it to have write ability over any other subsystem at all? Couldn't it just get one-way status updates from the other subsystems and then simply chose how to display them? I mean, sure, you can still write an evil car virus that gives the driver false speed information or hides the fact that the gas is running out. But a) that still seems less disturbing than an evil car virus that disables your breaks or pops out an airbag, b) you could always have emergency notification lights or beeping alarms not integrated with the infotainment system for really critical conditions (which for the most part, cars already do have).