WHILE SITTING IN TRAFFIC CONSUMER'S VEHICLE WAS STRUCK IN THE REAR, CAUSING IT TO STRIKE A ANOTHER VEHICLE IN THE REAR. CONSUMER SUSTAINED TORN LIGAMENTS IN THE NECK. REAR MIDDLE SEAT POSITION SEAT BELT HOLDING A CSS BECAME DETACHED ALMOST DISLODGING THE CSS WHICH WAS ANCHORED AT THE TOP BY A TETHER STRAP ATTACHED TO THE SEAT. *AK THE LATCH PLATE CAME OUT OF THE BUCKLE. SON CAN NOT REACH THE BUCKLE WHEN SEAT IN THE CSS. VEHICLE NOT TOTALED IN THE CRASH. ESTIMATED SPEED AT IMPACT WAS 30 MPH. JUST MINOR DAMAGE TO THE REAR BUMPER AND HATCH. STRIKING VEHICLE UNDER ROAD THE ENVOY. DEALER INSPECTED BUCKLE AND COULD NOT DUPLICATE THE ISSUE OF A POSSIBLE FALSE LATCHING.CW