A speed controller for toy vehicles on a toy car racetrack has a manual controller for varying an electrical driving voltage from an electric power supply for the car racetrack. The manual controller is manually displaced over a preset operating path so the driving voltage derived by the electric power supply varies from zero to a first preset maximum value below the voltage that is derived by the electric power supply. An additional controller responds to manual operation to set the driving voltage applied to the car racetrack, to a second preset value above the maximum driving voltage that is derived by the controller for varying the electrical driving voltage.