I would imagine that it is only for highways to start. It could also be handled in software if it was used for trips with sharp turns. The software in the lead car could indicate that the turn was initiated at this point in space and to turn hard when you get there. Presumably there is some kind of GPS that would help with that.

The real worry(though not too terrifying) is more about a rouge driver with a hacked transmitter mimicking a "professional driver" and sending them bunk data that could veer them into an accident. One way to mitigate this is by having some kind of sonar/radar/sensor on each car in the cardinal directions that would indicate if the command was safe. I am sure there are other ways to game the system that I am not seeing from this cursory reflection.