That's a mechanical side effect of the torque converter used in automatics, which even at engine idle with no acceleration input is able to transfer power to th

That's a mechanical side effect of the torque converter used in automatics, which even at engine idle with no acceleration input is able to transfer power to the drivetrain. The Toyota case was an instance of the car's engine control software unexpectedly commanding acceleration not requested by the user. In principle it could happen on a manual car as well, but most of Toyota's vehicles in the U.S. are automatics.