> avoiding large speed differentials That would be (or should be) the entire point of a posted speed limit, go with the flow. There should also be a lower spee

> avoiding large speed differentials That would be (or should be) the entire point of a posted speed limit, go with the flow. There should also be a lower speed limit. On roads I would bet many crashes occur due to the difference in speed between vehicles. Speeding motorcycles, slow trucks, fast sports cars, all of which would be around vehicles of moderate speed. The reaction time for the faster vehicle driver is different than the the drivers other slow vehicles. Also consider not all drivers have the same experience. Those differences are dangerous.