Mercedes Distronic intelligent cruise control. constantly measuring the distance between your car and the one in front of you.
Example you set the Cruise at 90km/h, some car cuts you off doing 70km/h the distronic sense the obstacle in front of you and adjusts the speed accordingly, it even brakes the speed down if neccesary the Distronic have access to 20% of the brakes potentional and can save many situations but its not idiot proof.
http://goo.gl/ek8Dj
