VEHICLE WAS TRAVELING IN TRAFFIC ON I-526 IN CHARLESTON COUNTY, SC. THE TRUCK IN FRONT OF ME PUT ON BREAKS DUE TO A TRUCK MERGING IN FRONT OF HIS VEHICLE. THE BRAKING SYSTEM IN MY CAR, BRAKED, THEN THE CAR LUNGED FORWARD AS BRAKES WERE APPLIED. IN ADDITION A VERY LOUD NOISE OCCURRED INSIDE THE VEHICLE WHICH WAS VERY STARTLING. MY VEHICLE ENDED UP UNDER THE TRUCK IN FRONT OF ME. THE FACT THAT THE VEHICLE LUNGED FORWARD AFTER THE AUTOMATIC BRAKING SYSTEM CAME ON AND THE LOUD ALARM IN THE INTERIOR WAS NOT WHAT HAD HAPPENED WITH THE SYSTEM BEFORE. ONE TIME BEFORE THE BRAKING SYSTEM APPLIED ITSELF AND THE DASHBOARD LIGHT CAME ON AND I SEEM TO RECALL THERE WAS A BEEP OR SOME SOUND THAT WAS VERY BRIEF.