^ related to people doing it in cars, I rented a rav4 with the auto/adaptive cruise control, it senses if theres a car ahead of you and will adjust to their speed and leave a safe distance. like 4 cars worth between you and the car in front.
Other cars could not handle a 4 car space between me and the car in front of me. Even though we were going EXACTLY the same speed, other cars seemed to feel an inescapable urge to fill that gap. Every time. Then my car would slow a bit to leave the proper safe gap between us and the car that just filled in there, and again somebody else had to fill that new space. dum