I PULLED MY 2014 TOYOTA PRIUS SLOWLY OUT OF A PARKING SLOT IN A SMALL PARKING LOT TURNING IT THE DIRECTION I WANTED TO GO ON A VERY SLIGHT SLANT DOWNHILL. BEFORE I COULD PUT IT IN DRIVE FROM REVERSE IT STARTED ROLLING DOWNWARD ON ITS OWN. WHEN I WENT TO APPLY THE BRAKES, THEY WERE SQUISHY AND DID NOT ENGAGE. I TRIED SEVERAL TIMES TO GET THEM TO ENGAGE BUT THEY NEVER DID. I WENT TO PUT THE EMERGENCY BRAKE ON BUT IT IS LOCATED SO HIGH UP IT WAS DIFFICULT TO GET MY FOOT UP THERE QUICKLY. MEANWHILE THERE WAS A TRUCK PARKED ACROSS THE END OF THE PARKING LOT LANE SO MY CAR ROLLED INTO THE TRUCK CREATING DENTS IN THE FRONT DOOR PANEL AND REAR DOOR PANEL. THIS WAS OBVIOUS BRAKE FAILURE. I WENT TO THE LOCAL TOYOTA REPAIR AND DEALERSHIP AND SPOKE WITH A SHOP EMPLOYEE. HE TOLD ME THAT THIS CAN ACTUALLY HAPPEN WHERE YOU CAN BACK A CAR UP AND TURN IT AND IT WILL GO ON ITS OWN (BUT IT SEEMS HE IMPLIED THAT THE "READY" LIGHT MIGHT NOT HAVE ENGAGED) AND THAT HE "HAD SEEN IT HAPPEN HIMSELF". IF THE TRUCK HAD NOT BEEN THERE, MY CAR WOULD HAVE ROLLED DIRECTLY OUT INTO ONCOMING TRAFFIC ON THE MAIN THOROUGHFARE THROUGH TOWN WHICH HAD THE HUGE POTENTIAL OF CAUSING A MAJOR ACCIDENT WITH INJURIES. I DID TRY TO RECREATE THE EVENT IN A NONPOPULATED AREA IN A VERY SAFE MANNER AND WAS UNABLE TO DO SO. THAT EVEN SCARES ME MORE!!! AS YOU HAVE NO IDEA IF IT CAN OR WILL HAPPEN AGAIN. I SPENT $20,000 PLUS FOR A NEW CAR THAT I AM ALWAYS HYPER-CAUTIOUS IN BECAUSE NO ONE WILL FESS UP TO PROBLEMS. IF