THIS WAS A FIRST TIME OCCURRENCE FOR MY 2007 PRIUS. I WAS STOPPED MIDWAY ON MY MOUNTAIN, LONG & STEEP, DIRT DRIVEWAY TRYING TO PARK ALONG THE ROCK SIDE. IT WAS TOO TIGHT TO PARK SO DECIDED TO CONTINUE DOWN TO THE BOTTOM. I WAS IN REVERSE AND SHIFTED, WITH MY FOOT ON THE BRAKE, INTO DRIVE. THE CAR SUDDENLY BOLTED FORWARD PROPELLING ME THROUGH THE FENCE AND DOWN A STEEP EMBANKMENT TO OUR DECK WHERE 12 PEOPLE WERE HAVING A DINNER MEETING. MY BRAKES DIDN'T WORK, NOR DID THE STEERING. THE BOLTING FORCE WAS HEARD BY ALL ON THE DECK. THERE IS NO WAY I WOULD HAVE PRESSED THE GAS BY MISTAKE FOR TWO REASONS: YOUR FOOT MUST BE ON THE BRAKE TO SHIFT; AND AS IS TYPICAL ON OUR STEEP GRAVEL ROADS, ONE NEVER PRESSES THE GAS PEDAL WHILE PROCEEDING DOWN. THE CAR PROPELLED 10 OR 12 FEET FORWARD CROSSING THE DRIVE AT A DIAGONAL, CRASHED THROUGH THE FENCE BOARDING THE DROP OFF, AND PROCEEDED DOWN THE EMBANKMENT STOPPING ONLY WHEN IT HIT THE BIG TREE BY OUR DECK. TO MY RIGHT WERE ALL THE GUESTS AND MY HUSBAND, JUST FEET AWAY FROM THE ONCOMING, OUT OF CONTROL CAR. HAD I MISSED THAT PARTICULAR TREE, I WOULD HAVE ROLLED DOWN AN EVEN STEEPER RAVINE BECAUSE OF ROCKS TO BOUNCE OFF AND VERY SHARP DROP OFF.*TR