Just this weekend I pulled over to the far left lane to pass some dude in the middle lane, going about 70, and as soon as I sped up a little and could see his front bumper in my passenger side mirror he sped up. Then I realized that he was racing or something, so I stayed in the left lane until he passed. After he got the satisfaction of winning "the race" he swerved over in between people in the slow lane and exited.