According to Sebastian Thrun from Stanford University, a previous winner of the DARPA challenge:
A robotic automotive vehicle — which, Thrun says, would "combine the convenience of a train with the convenience of a car" — is a long way from commercial viability...
..."This is the point in time where cars are really ready to become robotic," says Montemerlo, who unveiled Junior this year with Thrun at the American Assn. for the Advancement of Science meeting in San Francisco. "We're excited about the potential this might have for reducing the number of fatalities on the road. We're adding more drivers all the time but we're not adding new highways."
Read in full in 'Robotic cars could take pressure off nation's highways'