They say "completely distributed system" and "without a centralized control mechanism", so I wonder if they've worked through all the consistency questions (CAP theorem kind of stuff). I don't know how you safely deal with a network partition.

Imagine one car approaches an intersection and there are no other cars anywhere near. It gives itself a green and goes through the intersection without stopping.

Now imagine the same situation except there are two cars headed toward the same intersection at the same time, but neither one picks up the signal of the other. They both believe they are the only car headed toward the intersection, they both give themselves a green, and then they crash.

It seems like you either have to add some centralized infrastructure or accept that you are only safe to the extent that your radios are reliable.