Great question! I’m not sure and I’m excited to find out :-)
My guess is that a lot of the impact will be important but unnoticeable. For example, image sitting at a stop light and having a whole line of cars start simultaneously, because they’re all in communication together.
Or imagine a world without stop lights, because vehicles can communicate with each other and time their approach to intersections to weave between each other.
Of course, maybe it all devolves into hitting on the person riding in the car next to you :-P