I WAS PARKED ON A SLOPED DRIVEWAY (ABOUT 10 - 15 DEGREES). I STARTED THE ENGINE, STEPPED ON THE BRAKE PEDAL AND TOOK THE CAR OUT OF PARK INTO DRIVE. BRAKE PEDAL WAS NORMAL. I STARTED TO ROLL FORWARD AND WHEN I PUSHED THE BRAKE PEDAL THE CAR DID NOT SLOW. I SLAMMED THE BRAKE PEDAL AND IT WENT ALL THE WAY TO THE FLOOR. AT THIS POINT I WENT OFF THE END OF THE DRIVEWAY ONTO A 45 DEGREE DOWNWARD SLOPED LAWN; THEN INTO A WOODED AREA AT THE TOP OF A RAVINE. I SLAMMED INTO A TREE. THE CAR WAS JUDGED A TOTAL LOSS BY MY INSURANCE COMPANY. I DID NOT GET A BRAKE WARNING LIGHT. THE AIRBAGS DID NOT DEPLOY. THE CAR WAS SERVICED AT A UNION PARK GMC (WILMINGTON, DE) TWO DAYS PRIOR. INCLUDING BRAKE INSPECTION. CAUSE OF BRAKE FAILURE WAS DETERMINED TO BE RUPTURED BRAKE LINE. BOTH FRONT AND REAR BRAKES WERE FAILED. *TR