The push button shifters do not shift gears, unless the brake is depressed. On a slight incline, it is natural to shift from forward to reverse without braking leaving the driver in the wrong gear. So I have often started forward expecting to go backwards. I accidently ran over a portable toilet trying to quickly reverse out of a driveway on a slight incline. I hope no one has run over a person this way. I have had other close calls. This system is far more dangerous than lever style shifters. Even a little mistiming between brake and shift can leave the car going the wrong way.