A few years back a bunch of college students tested the system. The all lined up on an interstate and drove exactly the speed limit. Traffic was backed up for miles and they all ended up with tickets... for going the speed limit!

Here, if you're going 55 on the interstate - the speed limit - you are at a severe risk of being rear ended. I typically do 80 just to keep pace with traffic. I won't lie, I've occassionally used the fast lane to get somewhere and gone much faster...