DT: WHILE DRIVING ON INTERSTATE AT ABOUT 55 MPH SUDDENLY VEHICLE BEGAN TO SPIN OUT OF CONTROL IN RUSH HOUR TRAFFIC. THE CAR SPUN AROUND AND STRUCK A GUARD RAIL AND STOPPED IN TRAFFIC. NO PREVIOUS PROBLEMS WITH THE CAR. IT WAS TOWED TO PEP BOYS FOR REPAIRS, SERVICEMAN NOTED THE REAR DRIVER'S SIDE CONTROL ARM BROKE IN HALF. NO EXPLANATION AS TO WHY THIS HAPPENED, NOTED THIS WAS RARE. CAR IS CURRENTLY AT PEP BOYS FOR REPAIRS. CONTACTED HYUNDAI , WHO CLAIMED THERE WERE NO RECALLS ON THAT CAR AND THEY COULD NOT HELP.*AK