MATRIX REAR ENDED A MERCURY MOUNTAINEER AT ABOUT 35-40 MILES PER HOUR. THE ENTIRE FRONT END OF THE MATRIX WENT UNDER THE MOUNTAINEER'S BUMPER. THE ENTIRE FRONT END OF MATRIX WAS PUSHED BACK INTO THE COOLANT SYSTEM. BOTH HEAD LIGHTS WERE PUSHED INTO THE ENGINE COMPARTMENT. THE BUMPER WAS ALMOST DETACHED AND ON THE GROUND. THE HOOD WAS PUSHED BACK ON ITSELF ABOUT 3 FEET.THE AIRBAG DID NOT DEPLOY. MY DAUGHTER WAS DRIVING THE MATRIX AND HER HEAD HIT THE STEERING WHEEL. SHE SUFFERED A CONCUSSION. *TR