I hate to say this but.. There will never be autonomous cars. Human psychology, and unpredictability, will doom it all. We can build amazing AI technology, but we will never be able to account for Jenny after six mudslides in a Geo Tracker, or the random decision making of even the most well intention human driver.

Furthermore, if you haven't read "Industrial Society and Its Future"[0] you should. It makes a very good point that society as we know it today cannot and will not support a car-less reality.

[0]. http://editions-hache.com/essais/pdf/kaczynski2.pdf