Evan Ackerman:

Two and a half years later, reporters got to experience this “highway of the future” for themselves, on a test track in Princeton, N.J. Cars drove themselves around the track, using sensors on their front bumpers to detect an electrical cable embedded in the road. The cable carried signals warning of obstructions ahead (like road work or a stalled vehicle), and the car could autonomously apply its brakes or switch lanes as necessary. A special receiver on the dashboard would interrupt the car’s own radio to announce information about upcoming exits.
 
 Pictured above is an experimental autonomous car from General Motors, in which the steering wheel and pedals had been replaced with a small joystick and an emergency brake. Meters on the dashboard displayed the car’s speed as well as the distance to the car in front.