Any specific suspicious death may come and go, but the fact that something like this is believable with conventional networked cars is enough reason to be very skeptical of security and government access (and criminal access) claims of manufacturers, no matter how well-meaning.
Ultimately, I am alive because nobody cares enough to murder me.
I don't see what's wrong with having fewer things in your life which can silently kill you.
If you get in a new car, you are now completely at its mercy. There are few or no precautions you can take; you might as well lay on your back, and strap your arms down so your belly stays up.
What you're really doing is making it cheaper and easier to kill, misdirect, or trick you. This means that people who wanted to do these things before, but couldn't afford it, now can.
Humans learn by using data from their interactions with the environment, since childhood. That's a ton of data and there might not be a way around that.
Given that humans do without detailed data of this sort, I think it should be okay to leave manufacturers and service providers to figure out how proprietary or standardized the datasets should be.
I personally might never trust/desire an autonomous car, especially one connected to the internet, a phone network, or a car-to-car network. In a world where everyone has your best interests at heart, it seems like a nice feature; in the one world we've got, it doesn't.