I WAS IN WILLIAMS, AZ ON MAY 27, 2009. AT THE RAILROAD RV PARK. GOT INTO MY 2008 PRIUS TO RETURN TO CONRESS AND IMMEDIATELY SMASHED INTO A POST ABOUT 50 FEET FROM MY STARTING POINT. IT HAPPEND SO FAST I DON'T KNOW HOW IT HAPPENED. DIDN'T EVEN HAVE A CHANCE TO APPLY THE BRAKE. FILED AN ACCIDENT REPORT REPORT WITH THE WILLIAMS POLICE DEPARTMENT SINCE THERE WAS PROPERTY DAMAGE TO THE RV POST AND MY PRIUS. HAD MODERATE DAMAGE BUT WAS ABLE TO LIMP BACK HOME. REPAIRED MY PRIUS AT A LOCAL COLLISION SHOP. DROVE DOWN TO THE PHOENIX, AZ, AREA (ALMOST 55 MILES FROM HOME) ABOUT TWO MONTHS AGO. AFTER ABOUT THE LAST 20 FREEWAY MILES I SAW TRAFFIC STOPPED AHEAD AT A STOP SIGN. STARTED TO APPLY THE BRAKES AND NOTICED THAT I DIDN'T SLOW IMMEDIATELY. FINALLY ENDED UP ONLY ABOUT 50 FEET FROM THE CAR AHEAD. HAD TO AGGRESSIVELY APPLY THE BRAKES WHEN I SAW I WASN'T STOPPING AS SOON AS I THOUGHT. WAS RELIEVED WHEN I DIDN'T PLOW INTO THAT CAR AHEAD THIS SAME OCCURANCE HAPPENED AT LEAST ONCE EARLIER BUT WAS NOT AS FIGHTENING. SOMETIMES, WHILE STOPPED AT A LIGHT, I HAVE A FEELING THAT SOMEONE BUMPED ME IN THE REAR, BUT I HAVE NEVER BEEN BUMPED. THIS IDENTICAL PROBLEM EVEN OCCURRED WHEN I HAD MY 2002 PRIUS. MOST SERVICE MANAGERS SAY "IT IS NOTHING TO BE WORRIED ABOUT". WAS HOPING TO HAVE BEEN ABLE TO WAIT UNTIL THEY PRODUCED A "PLUG-IN" PRIUS BUT I PROBABLY WON'T EVER BUY A TOYOTA PRODUCT AGAIN. I AM REALLY WORRIED ABOUT A FUTURE ACCIDENT IN MY PRIUS AND HATE TO DRIVE IT.