ACCELERATING WHILE ENTERING A FREEWAY, TOOK FOOT OFF THE GAS AND THE VEHICLE CONTINUED TO ACCELERATE. APPLIED BRAKE BUT VEHICLE CONTINUED TO ACCELERATE. PUT VEHICLE IN NEUTRAL TO TRY AND SLOW DOWN AND AGAIN APPLIED BRAKE. VEHICLE BEGAN TO SPIN TO THE RIGHT AND WE HIT THE GUARD RAIL, HITTING THE PASSENGER REAR BUMPER AND THE DRIVER'S SIDE FRONT BUMPER. SIDE AIR BAGS DEPLOYED. CAR SPUN INTO THE MIDDLE TRAVEL LANE AND BEGAN TO SPIN AROUND. CAR WAS SLOWING DOWN AND WAS ABLE TO TURN CAR OFF. FORTUNATELY NO OTHER CARS WERE INVOLVED. AN OFF DUTY SHERIFF'S DEPUTY STOPPED AND SAID HE NOTICED SMOKE AND THOUGHT THE CAR WAS ON FIRE BUT NO FIRE OCCURRED. WHEN STATE POLICE ARRIVED THEY ASKED US TO MOVE THE CAR TO THE BREAK DOWN LANE. WAS ABLE TO PUT CAR IN REVERSE AND BACKED CAR TO BREAKDOWN LANE. TRIED TO PUT CAR IN DRIVE BUT CAR WOULDN'T GO FORWARD. *TR