Google has been testing self-driving cars on roads in California, according to a report, and so far they've avoided everything but a minor fender bender--caused by a human-driven car.

The New York Times reports that seven test cars have traveled 1,000 miles without need for human intervention (a driver has been stationed behind the wheel just in case, accompanied by a technician to monitor the navigation system), and that they've covered more than 140,000 miles with the human chaperone stepping in only occasionally. One of the cars was even able to safely make its way down Lombard Street in San Francisco, the fabled "crookedest street in the world," the Times says.

'Stanley,' devised by Sebastian Thrun and his team from Stanford, won the DARPA Grand Challenge in 2005.

(Credit: Stefanie Olsen/CNET)

Google's robot car is equipped with artificial-intelligence software; a rotating sensor on its roof, which can scan more than 200 feet in all directions to create a 3D map of the car's environs; a video camera mounted behind the windshield, which helps the navigation system spot pedestrians, bicyclists, and traffic lights; three radar devices on the front bumper, and one in the back; and a sensor on one of the wheels that allows the system to determine the car's position on the 3D map, the Times says. The car also features a GPS device and a motion sensor