When stopped at a stoplight, in unbridled mode with one pedal driving engaged, the car surged forward on it's own. The surge forward caused my vehicle to rear-end another vehicle. I would assume the failure was the one pedal driving system and it is available for inspection. The problem has not been reproduced or inspected yet, but we have an appointment for a Ford dealer to evaluate the car. The only warning was the pre collision warning which did go off.