2002 VOLKSWAGEN PASSAT WAGON / 92350 MILES PLACED IN "PARK" ON A SLIGHT INCLINE (PARKING BRAKE NOT USED). ENGINE WAS TURNED OFF AND THE KEYS WERE REMOVED. DRIVER STEPPED OUT OF THE CAR AND A FEW SECONDS LATER CAR STARTED ROLLING BACKWARDS WITH CHILDREN (AGES 3 AND 10 MO) IN THE CAR. DRIVER JUMPED IN CAR TO SET THE BRAKE, BUT FELL ON STREET AS CAR ROLLED. CAR CROSSED STREET AND HEADED DOWN A STEEPER INCLINE HITTING BUSHES, CROSSING ANOTHER DRIVEWAY, AND FINALLY HITTING A ROCK WALL COMING TO A STOP. CHILDREN WERE OK. DRIVER HAD BRUISES / SCRATCHES FROM FALLING ON PAVEMENT. CAR SUSTAINED $3,400 IN DAMAGE. NEIGHBORS VERIFIED CAR WAS IN PARK, AND OWNER MANUAL STATES THAT KEYS CANNOT BE REMOVED WITHOUT THE CAR BEING IN PARK ( KEYS WERE OBSERVED BY SEVERAL NEIGHBORS TO BE OUT OF THE CAR). VOLKSWAGEN OF AMERICA ASKED ME TO GO TO A DEALER FOR PROBLEM DETERMINATION. DEALER TRIED PARKING THE CAR 5 TIMES ON UPHILL AND DOWNHILL INCLINES, AND PARK HELD. THEY ALSO CHECKED THE COMPUTER AND FOUND NO FAULTS. NO ATTEMPT WAS MADE TO CHECK THE INTERNALS OF THE TRANSMISSION, TO DETERMINE WHETHER THE INCLINE WAS THE SAME AS THE DRIVEWAY WHERE IT OCCURRED, OR TO DETERMINE WHETHER THERE WAS A REASON FOR AN INTERMITTENT PROBLEM. VW OF AMERICA STATED THAT THE DEALER HAD FOUND THE CAR WAS IN SPEC (WITH THE 5 HILL TESTS AND COMPUTER CHECK), AND NO FURTHER ACTION WOULD BE TAKEN. VW STATED THAT WE SHOULD ALSO HAVE BEEN USING THE PARKING BRAKE ANY TIME WE PARK (WE DO ON STEEPER HILLS, BUT NOT ON