Speaking from a little bit of experience in this area...these networks are often not isolated. It depends on the vehicle and network architecture, but there ar

Speaking from a little bit of experience in this area...these networks are often not isolated. It depends on the vehicle and network architecture, but there are valid business reasons for getting at the entire network through Wi-Fi. Buffer exploits in C aren't the issue. The issue is cracking the weak encryption scheme, and figuring out the unpublished sequence of CAN bits to send that do things like lock/unlock doors or change the powertrain calibrations. OEMs try to hold this info close to the vest for obvious reasons, but there is a large subculture out there reverse engineering it.