What the Future of Driverless Cars Will Actually Look Like

We've heard a lot about the projected benefits of driverless cars (whenever we get them, that is). The roads will become safer, as we remove distracted, flawed drivers (and human error) from behind the wheel. Congestion will decrease, as cars that drive themselves and communicate with each other are able to more efficiently share roadways. Fuel economy will go up as a result, and emissions will go down. We'll need to devote less space to parking, as automated vehicles come to function more like public transit, remaining perpetually in motion. And all kinds of people who can't currently drive – the young and old, as well as the disabled – will become more mobile.

Which is all well and good. But exactly how many fewer crashes are we talking? How much money and gas and time would we save? Can we get some numbers, please?