I agree, but I'm not sure we can afford to wait ~5+ years for self driving cars; on the other hand that's probably how long it'll take to build more subways, at a minimum. Whatever is done it needs to be done immediately.
Self driving cars are still subject to congestion in identical ways because they take up just as much space and need safe distances between cars. It also adds noise & pollution, not to mention the fact that the energy to build a car is really really large (and they don't last as long per total miles per person).
As linked to above, see this gif: http://i.imgur.com/kw8DaST.gif