"I hope these self-driving cars will be able and designed to work while completely offline, with no built-in way to ever connect to a network."

Don't hold your breath about that. There will be a huge load of data ready to be sold to advertising companies just by listening what passengers talk about when passing near areas/stores/billboards/events etc.

> receive ads to show you

I'm just envisioning a scenario where the car automatically pulls to the side of the highway, locks the doors and dishes you with a 15 second ad, and then the doors unlock and the journey resumes as normal.

Or just (virtually) replace billboards with personalized content

Using these cars to commit homicide was actually one of the plot points in the second book of Three Body Problem trilogy by Liu Cixin. Very much recommended if you are into sci-fi.

Those books are interesting in that Liu seems to get away with seriously portraying narratives that would be out of bounds in the "approved" popular culture of the West. Murder by robocar is a minor example, but others include portrayal of the inherent weakness of societies in which men are effeminate and the superiority of leaving strategic decisions to military authorities. (I don't particularly agree with those propositions, but they are certainly present in the books.)

I'm half-way done with the last book in the trilogy and I am finding the assumptions and viewpoints of the world from a Chinese view quite interesting. The one that struck me most was how he presents humanities greatest strength over the technologically superior aliens is the human ability to conceal their true thoughts and the possibility of deception. Quite different from Christianity's high value placed on honesty.

The great stories of paganism and animism were composed by artists, and they all feature trickery and uncertainty. The Christian Bible has some of that (I like Job), but the majority was written by humorless unimaginative prudes. I suppose some of the Chinese philosophers are a little better than St. Paul, but mostly when they're being playful.