Civilians used to own canons. For blowing up ships. And the occasional home invader. Doesn't matter if it has sailed if we sink it. We should sink that ship.

You don't need a high bandwidth connection to do emergency notifications, and considering it might be in a remote area satellite would be better than LTE.

For the diagnostics you could log events internally and then collect them with OBD-II readers, though I'd like to force car makers to use open data formats so people can see for themselves what's collected.

That said, this data should be limited in scope and use...

Yep, anonymized, limited, non-distributable, and secured, with severe penalties (on the order of tens of thousands of dollars per person, paid to the harmed party) for failure to adhere.