The 2012 Audi A7 also offers an adaptive radar-based cruise control system that not only maintains a set speed and distance from the traffic ahead on the highway, it can operate as efficiently in stop and go traffic.

FORBES: 2012 Audi A7 Review: Elegant Performer

Some luxury cars already contain adaptive cruise control, which uses radar or laser-based sensors to track the movements of vehicles on the road ahead.

ECONOMIST: MONITOR

In addition, Mercedes-Benz has already equipped this innovative electric car with the radar-based collision warning system COLLISION PREVENTION ASSIST with adaptive Brake Assist as standard.

ENGADGET: Mercedes-Benz introduces B-Class Electric Drive, we go eyes-on

Radar embedded in the front of the Fusion sweeps the road ahead and when the adaptive cruise control is activated the car automatically slows down as it approaches another vehicle within a certain distance and then speeds up when the gap widens.

FORBES: Automakers On The Road To Self-Driving Cars