[NoMoreNicksLeft]

I can't prove it, but I suspect (strongly) that whichever method you believe to be the correct one, following distances must shorten dramatically, or speeds must drop so low as to threaten traffic jams (which, perversely, leave everyone bumper to bumper). It's all about how many cars are trying to use that stretch of road for a period of time, and if all are to fit through within that window, there is both a minimum speed and a maximum following distance. Wish I wasn't a math flunky.

[CrispyKerosene]

I think most people are just unaware of how much distance is required between to cars at highway speeds to considered safe. A proper buffer would leave lots of room to absorb the extra cars and loss of speed. That the point, its flexible and elastic.