Comment by usrusr

That could be more than just a joke though: special lanes for computerized slipstream driving could make cars and trucks approach railroad efficiency. A "driver agent" posts its itinerary to the routing network, finds peers going the same direction at roughly the same time, accelerates/decelerates to find them and hook (contactlessly) into the moving paceline, at a position that fits the vehicle's frontal area (you wouldn't want small cars breaking the slipstream between trucks). The routing network bills some of the slipstream savings on behalf of the vehicle(s) in less favorable positions at the front.

Like the visionary dream of individually routed rail cars, but built bottom-up, with cars/trucks that are perfectly useful in standalone driving on regular roads. And it could scale even closer to rail: perhaps some long-haul connections get metal rails integrated in the floor like tram rails, that some long-haul trucks with a special bogey option could slot in, in the fly? That would be an impressive stunt if performed by humans, but easy for computers. Perhaps some connections add overhead wires? Perhaps some trucks, with the overhead wire pantograph option, add a robotic power handover arm because that's cheaper than wear and tear on two pantographs? Could all start bottom up, with few installations.