The road to DARPA's Urban Challenge

Two years after its last Grand Challenge, the U.S. government's Defense Advance Research Projects Agency is gearing up to host the Urban Challenge, a race between autonomous, driverless cars through a simulated urban environment at George Airforce Base in Victorville, Calif. Thirty-five vehicles will compete in the National Qualifying Event semifinals between October 26 and 31, with 20 vehicles going on to compete in the final race on November 3. Here is a roundup of some of the contenders.