Via Distance

As one example, when the distance between cars is made small, it's called tailgating, and I've already discussed it at length, in Via Tailgating.

As another example, consider the following situation, in which cars A and C are overtaking car B.

I discussed the exact same situation in Via Lane Change, and said that when I'm playing the role of A, and want C to go ahead of me, I like to signal by tapping my brakes. Sometimes, though, I do something different, and signal by just maintaining my distance from B.

Since distance, or relative distance, is the integral of relative speed, I suppose one could argue that communication via distance is the same thing as communication via speed, or via change in speed, but they sure seem different to me. Perhaps the difference is that distance applies to cars in a single lane, while relative speed applies to cars in adjacent lanes.