ON 09-12-16 I WAS INVOLVED IN A REAR END COLLISION (35+ MPH). I WAS STOPPED IN TRAFFIC (INTERSTATE HIGHWAY). MY VEHICLE WAS IN ECO MODE AND THE VEHICLE'S BRAKE HOLD FEATURE WAS ACTIVATED, THE BRAKE WAS FULLY ENGAGED/PRESSED, AND HOLD WAS DISPLAYED ON THE FORWARD INSTRUMENT CLUSTER. WHILE STOPPED, ANOTHER VEHICLE STRUCK MY VEHICLE FROM THE REAR. MY VEHICLE'S NECK-PRO RETRAINT SYSTEM ACTIVATED AND THE HAZARDS ACTIVATED. NO AIR BAGS WERE DEPLOYED. HOWEVER, A FEW SECONDS AFTER THE ACCIDENT, THE BRAKE HOLD FEATURE DEACTIVATED AND MY VEHICLE BEGAN TO ROLL INTO RUSH HOUR TRAFFIC. AFTER ACTIVELY PUMPING THE BRAKES, TO NO AVAIL, I INITIATED AN OFFENSIVE MANEUVER AND SWERVED THE VEHICLE OFF OF THE HIGHWAY AND ONTO UNPAVED SIDE ROAD/SHOULDER. MY VEHICLE CONTINUED TO ROLL FORWARD AND ONLY STOPPED AFTER I FULLY PRESSED/ENGAGED THE EMERGENCY BRAKE. IS DEACTIVATING BRAKE HOLD IN A REAR END COLLISION A DESIGN FLAW, OR IS THIS THE INTENDED FUNCTION?