I do pay close attention how many folks are pacing me, falling behind me, or passing me. My goal is to generally never be in a pack of cars. I try to keep myself between packs and so pay attention to what the packs are doing If there's an excessive fast individual, I sometimes will accelerate just long enough to see how fast they are going, then drop back. and I can tell you that my average of about 8-9mph over the limit is a couple mph shy of the average in the left lane, given how often I have to get over to let folks pass. I set my cruise at about 63-64, and while I'm usually passing the traffic on the right, it's not by a huge margin. And anyone doing 55 is causing is huge issue, as they will have people backed up behind them. I'll bet the SHA has a survey on file showing the 85th percentile, and thats it's not 55mph. But it's not 80 either, I'll bet