I think it's plausible. I believe a lot of traffic would disappear if people drove the same speed. I do a lot of highway driving and use cruise control, and I see lots of cars go faster, then slow down, then go faster, then slow down, etc, causing more lane changes and probably annoying other drivers. Lane changes takes up two spaces and causes others to slow down creating a domino effect.

Traffic is one of those things where if everyone else looked out for each other, waited their turn, let people merge, etc, then everyone would get to their destinations sooner.