[Animats]

Self-driving cars don't really need to talk to "the cloud" much, if at all. They need some map data, and they might contribute to map data. They can use some traffic data, and can contribute to traffic data, which needs about as much data as Waze. None of this is real-time; it can be seconds or minutes behind.

Transmitting all the car's imagery to servers is an R&D activity. Google downloads all that from their vehicles to train their machine learning systems, but training is an offline process. Production vehicles might occasionally upload "interesting" imagery they didn't recognize, or data from situations where there was trouble, but there's no need to upload it all.

[sharemywin]

How do 2 cars cruise 60 mph through a 4 way stop without talking with each other.

[quasse]

That's a bit different from talking to "the cloud" as the parent poster was talking about. Cars will be using a short range radio technology like DSRC (5.9ghz band) to communicate locally. The FCC and DOT are already pushing mandates to have cars equipped with it.

[Animats]

Nobody is seriously trying to do that in a production vehicle. That would apply only to a highway system with all cars automated. Like this.[1]

[1] https://www.youtube.com/watch?v=zm_rlLyelQo

[sbierwagen]

https://en.wikipedia.org/wiki/Vehicle-to-vehicle

Talking to other cars is different from communicating over the internet.