Increased density of cars on the road has the potential for a huge economic wins, in terms of getting governments out of widening highways to increase throughput.
Automated cars would be be able to (one day) receive information about down-the-road conditions and congestion which would enable the automation of William Beaty's "jam busting" techniques at a more expansive scale: http://amasci.com/amateur/traffic/trafexp.html (For example, slowing down gradually, rather than screeching to a stop as you pile into the back of a jam.)
Automated cars would be be able to (one day) receive information about down-the-road conditions and congestion which would enable the automation of William Beaty's "jam busting" techniques at a more expansive scale: http://amasci.com/amateur/traffic/trafexp.html (For example, slowing down gradually, rather than screeching to a stop as you pile into the back of a jam.)