Somewhat OT.....but check out this video.....
http://www.autoblog.com/2008/03/21/v...in-experiment/

What camp do u fall in. Do you hang back during rush hour or keep it fairly close to the bumper. I try to hand back far enough without needing to use the break and coast along with the speed of whatever I'm stuck at but of course, someone will always find that spot another place to cut and move ahead....