The accident happened when I was using the "BRAKE HOLD SYSTEM". It is designed to use when the needs to stop briefly. When the Brake Hold button is touched while the driver's foot is on the brake pedal, the driver do not need to step on the brake even though the shift lever is in D. After I finished paying for a car wash, I touched the Brake Hold button. Then the vehicle suddenly accelerated forward and ran at a high speed. I was pushing the brake pedal, when I touched the button. I was startled and attempted to stop the vehicle with all my strength by braking the brake pedal. It didn't stop and went over the cub and accelerated even more and it crossed the both lanes and hit the cub on the other side. It climbed up the bank wall and it finally stopped. The police and the ambulance came and took me a hospital. I later found out the vehicle was towed to a nearby junk yard. I believe that the new high-tech system known as BRAKE HOLD malfunctioned and caused "unintended acceleration". I believe that it certainly is extremely dangerous. It has not yet been inspected by the Lexus mechanics. There were no warning signs whatsoever before the unintended acceleration. BTW, I have used the function before i.e. when I used drive throughs.