CONTACT IS OWNER OF 2008 GS 350 LEXUS. WHILE ATTEMPTING TO TURN THE VEHICLE INTO A PARKING SPACE @ APPROXIMATELY 15 MPH -- THE VEHICLE ACCELERATED SUDDENLY ON IT'S ON WITHOUT WARNING. VEHICLE HIT AN EMBANKMENT & VEHICLE BOUNCED BACK/FORTH ON THE EMBANKMENT, CAUSING SUBSTANTIAL NECK PAIN FOR BOTH THE DRIVER AND PASSENGERS. PRESSING THE BRAKE PEDAL DID NOT STOP THE VEHICLE & THE AIRBAGS DID NOT DEPLOY. THE FRONT OF THE VEHICLE WAS DAMAGED BUT WAS ABLE TO DRIVE HOME SLOWLY. LEXUS DEALER WAS TOLD OF INCIDENT & RECOMMENDED TAKING VEHICLE TO A LOCAL TOYOTA DEALER WHO COULD FIND NOTHING WRONG WITH VEHICLE. TIME TO TRADE VEHICLES WITH A COMPETITOR.