According to China Daily, back in July, a Chinese driverless car traveled about 175 miles, at around 55 mph, on an expressway laden with other cars. Even more impressive, the car needed no GPS assistance, instead relying on only video cameras and radar sensors to see the road and the other drivers.
The car, a Hongqi HQ3 developed by the National University of Defense Technology, was controlled by a proprietary artificial intelligence system in the car's trunk. It seems like the demo went swimmingly: the car managed to travel the long distance between provincial capitals Changsha and Wuhan, passing cars and changing lanes, with hardly a hiccup.
Of course, as the car relies primarily on visual clues, the demo was conducted during daytime--a lack of light, as well as weather complications like fog, can throw the car's senses off. (Maybe it could use one of these optical sensors?)