Well, this is about as stupid as you can get. Why, oh why, do any of these systems require access to a network at all? Cars have worked just fine, in principle and practice, for a VERY LONG TIME. The addition of SOME electronics and tiny computers to control and maintain certain aspects has been reliable. At some point, however, some bozo figured it would be even smarter to let other people talk to cars. Why?! Money.
There doesn't need to be any connection between the passenger-specific systems and those that control the cars systems. There's no way in hell any dashboard entertainment system should have the ability to access any of the cars functions, and that goes for 2G dongles from insurance companies, too. You want data from the car? Then tell the car that it will dump raw data at a specific time and not take any inputs. Period. Then you can do anything you like with the data.
Seriously! A computer in a car should be about as connected to the car as a laptop would be if you were sitting in the car using it on your lap. I'd like to see hackers cut the brakes, then.