"Feel this," says Schlegel, pointing to a silvery box next to the Dream Car. Normally, this control box in its aluminum housing full of cooling ribs, connections and plugs is hidden deep inside the vehicle. The heat radiating from it indicates intensive computing activity. "We feed the car with an alternative reality based on sensor data from a drive through Friedrichshafen," explains Schlegel. The control box heats up because it is processing the data live. It evaluates signals from front, side and rear cameras, LIDAR and radar sensors as well as GPS map and position information just as it would during a real drive. The ZF engineers recorded the data on a one-and-a-half-kilometer stretch of road between the company's research center and its headquarters in Friedrichshafen. The route is full of challenges for an autonomous vehicle. It includes a lane for cyclists, two bus stops, three roundabouts, two sets of traffic lights and five pedestrian crossings. In other words, a normal urban scenario. Autonomous driving on an empty US highway is no great technical challenge. However, in busy European city traffic, it's a different story. This is where the sensors generate a flood of signals the software has to rapidly and correctly interpret: "Our algorithms turn this vast volume of data into a true image of the traffic. That's the vital basis for an autonomous vehicle that allows it calculate and steer its way through heavy traffic."