Sudden acceleration. I was stopped in my driveway (flat surface). The car started to roll forward and I pressed brake hard. Vehicle came to a complete stop but when I removed my foot from brake car lurched forward. Car hit a retaining wall approximately 3 feet away before I could stop it again by braking hard. When the car was put in park I was able to remove my foot from the brake without it lurching forward again. Little personal safety risk in this situation in my driveway with no other people around. the car hit the retaining wall at relatively low speed when it lurched forward.