I WAS IN THE PASSING LANE ON A FOUR LANE INTERSTATE HIGHWAY DRIVING OVER AN OVERPASS NEAR ROCKPORT, MO. MY SPEED/CRUISE CONTROL WAS SET ON 70 MPH.THERE WERE ONE OR MORE CARS AHEAD OF ME IN THE PASSING LANE AND I WAS PASSING A SEMI-TRUCK IN THE RIGHT LANE. MY VEHICLE STARTED TO SPEED UP, WITHOUT ANY INPUT FROM ME. I TRIED MULTIPLE TIMES UNSUCCESSFULLY TO BRAKE AND COULD NOT SLOW THE VEHICLE DOWN. I CHANGED LANES IN ORDER TO NOT HIT THE CAR IN FRONT OF ME WHICH WE WERE ALMOST UPON. IN DOING SO, THE SEMI-TRUCK CLIPPED THE CORNER OF THE VEHICLE. I WAS SPUN ON TO THE SHOULDER AND THEN ROLLED SEVERAL TIMES DOWN THE 65 FOOT EMBANKMENT. THE VEHICLE WAS TOTALED. THE PASSENGER SUSTAINED BRUISING AND LOSS OF CONSCIOUSNESS. HE HAD TO BE EXTRICATED FROM THE VEHICLE AND WAS TAKEN BY AMBULANCE TO A NEARBY HOSPITAL AND THEN SUBSEQUENTLY AIRLIFTED TO ANOTHER HOSPITAL. I SUSTAINED A COMPOUND FRACTURE IN MY CLAVICLE, 5 BROKEN RIBS AND A CRACKED PELVIS. I WAS HOSPITALIZED FOR THREE DAYS.