No doubt today, but in another very realistic in the sense that's perfectly logic and possible since more than a decade, where government have digital IDs who are smart-cards not crapplications, and with them certified mails with a personal domain and the ISP router is just a FLOSS homeserver (as it is actually, being GNU/Linux embedded machines with a tailored PBX, Samba to offer usb network storage, CUPS for serving a usb-connected printer and so on, just a bit more powerful and open.
In such world thanks to the commonality of FLOSS we have dedicated distros and package for such iron, widespread enough to be commonly available in users hands. As a result the security risks are still more than zero but much, much less and many who could since their car is their own, not owned for real by the OEM, they could simply cut the connection if they do want so.
Such open world could be done in few years by laws, and anything is already there since decades. It's a matter of knowledge and will.
