Children's ride-on vehicles having improved motor assemblies. The vehicles are reduced-scale vehicles, often formed substantially from molded plastic, that are sized for use by children and which include battery-powered motor assemblies. The vehicles may include a noise-suppression device that is adapted to reduce electromagnetic noise, a cutoff device that is adapted to selectively restrict operation of the motor assembly, or both devices. In some embodiments, the cutoff device may be a temperature-sensitive cutoff device and/or a current-sensitive cutoff device. In some embodiments, the device is disposed within a motor housing provided with the vehicle.