WHILE ON THE STREET AS I WAS BACKING MY CAR INTO A PARKING SPACE ADJACENT TO THE STREET CURB THE CAR SUDDENLY ACCELERATED IN REVERSE AT HIGH SPEED, CRASHING OVER THE CURB AND SIDEWALK, REAR END FIRST. MY STEPPING ON THE BRAKES IN AN ATTEMPT TO STOP THE CAR WAS UNSUCCESSFUL; THE CAR DID NOT COME TO A STOP UNTIL IT CRASHED INTO AN IRON FENCE WHICH BORDERED THE YARD CAUSING DAMAGE TO THE FENCE AND THE CAR. A SIMILAR INCIDENT OCCURRED QUITE A FEW YEARS AGO WHEN THE SAME CAR SUDDENLY ACCELERATED IN REVERSE OUT OF CONTROL AND I WAS UNABLE TO BRING IT TO A HALT UNTIL IT HIT A PARKED CAR. I DO NOT KNOW WHAT CAUSED EITHER OF THESE INCIDENTS TO OCCUR.