Cars out here tend to clump too. I will, if possible, get out of the clump, generally by slowing a tiny bit (e.g., I'm going 82 and the clump is going 90 I don't have to slow at all, but if the clump is going 82 I'll slow to 80 or less). Druther drive in my own clump, since I know my driving skills.

(That's on the Interstate, of course. Non-Interstates have lower speed limits.)