2015 MODEL S 85D WAS REVERSED ONTO DRIVEWAY THEN PLACED IN PARK AND DOORS WERE CLOSED AND LOCKED. A FEW MOMENTS LATER THE VEHICLE STARTED ACCELERATING FORWARD TOWARDS THE STREET AND CRASHED INTO A PARKED CAR. FRONT WHEELS WERE RECEIVING POWER WHILE REAR WHEELS WHERE LOCKED AND DRAGGING RATHER THAN WHEELS SPINNING. I REVERSED VEHICLE BACK ONTO DRIVEWAY AND IT HAPPENED ANOTHER 2 TIMES AFTER FIRST INCIDENT WITHIN A 30 MINTUE TIME SPAN.