ON 8/29/12, I GOT INTO MY 2008 PRIUS IN THE PARKING LOT OF THE EASTON, MD GIANT FOOD-STORE TO RETURN HOME. THIS LOT IS ON A SLOPE JUST ABOVE A PARKING LOT FOR WALMART, WITH A PAVED ROAD BETWEEN THE 2 LOTS. THE PARKING LOTS WERE VERY CROWDED. I NEEDED TO GET TO THE ROAD SEPARATING THE 2 LOTS IN ORDER TO GO HOME. I HAD JUST STARTED THE PRIUS AND PUT IT INTO DRIVE WHEN IT STARTED TO ROAR LOUDLY, JUMPED OUT FAST, AND ACCELERATED RAPIDLY, EVEN THOUGH I BRAKE MULTIPLE TIMES. THE BRAKES SEEMED TO MAKE IT ACCELERATE FASTER. I WAS NOT TOUCHING THE GAS PEDAL, ONLY THE BRAKE, BUT THE CAR WAS ROARING AND OUT OF CONTROL. ON THE WAY OUT OF THE GIANT LOT, THE PRIUS HIT 3 CARS. THE NOISE WAS VERY LOUD, AND THE CAR WAS OUT OF CONTROL. PUMPING THE BRAKES OR HOLDING THEM DOWN DID NOTHING TO SLOW THE CAR, AND THE NOISE WAS TERRIFYING. THE BRAKES DID NOT WORK, AND THE PRIUS CONTINUED TO MAKE A VERY LOUD ROARING NOISE. THE SPEED OF THE CAR MADE STEERING DIFFICULT, IF NOT IMPOSSIBLE, AND THERE COULD HAVE BEEN INJURIES. THE PRIUS THEN LEFT THE GIANT PARKING LOT, WENT DOWN THE MULCHED SLOPE, CROSSED THE STREET, BUMPED OVER THE CURB, AND WENT UP THE WALMART SLOPE HITTING A SMALL TREE. THE CAR WAS PROBABLY GOING AT LEAST 40 MPH AND CAME TO A STOP ONLY AFTER IT PLUNGED INTO AN UNOCCUPIED BLACK CAR PARKED IN THE WALMART PARKING LOT. IT WAS SEVERELY DAMAGED AND TOWED AWAY. NO ONE KNEW WHO THE OWNER WAS AT THE TIME THE POLICE ORDERED IT TOWED AWAY. AN OCCUPANT WOULD HAVE BEEN SEVERELY INJURED O