While accidents caused by a mistaken press of the accelerator pedal have been alleged for nearly every make/model of vehicle on the road, the accelerator pedals in Model S, X and 3 vehicles have two independent position sensors, and if there is any error, the system defaults to cut off motor torque. Likewise, applying the brake pedal simultaneously with the accelerator pedal will override the accelerator pedal input and cut off motor torque, and regardless of the torque, sustained braking will stop the car. Unique to Tesla, we also use the Autopilot sensor suite to help distinguish potential pedal misapplications and cut torque to mitigate or prevent accidents when we’re confident the driver’s input was unintentional. Each system is independent and records data, so we can examine exactly what happened.
We are transparent with NHTSA, and routinely review customer complaints of unintended acceleration with them. Over the past several years, we discussed with NHTSA the majority of the complaints alleged in the petition. In every case we reviewed with them, the data proved the vehicle functioned properly.
Source: tesla.com