You see people in the left lane, and as long as they are on the speed limit, they stay there. Get in the right lane and let people pass you - let the police worry about somebody who wants to speed. Don't force them pass in the right lane and zig zag, which can create an accident, just because you think you're correct.
When a car's ahead of you, as long as you can see it, you get a tow, just like the draft in NASCAR. Even if it's a long ways down the track, it punches a hole in the air that has to help. When you're running alone, you can feel the difference, and it shows on the clock, too.