More significant factor in developing this device was the 35 mph (56 km/h) speed limit imposed across the US during World War II to save on gasoline use and reduce tire wear.[2] A mechanism controlled by the driver provided resistance to further pressure on the accelerator pedal when the vehicle reaching the desired speed.[2] Teetor's idea of a dashboard speed selector with a mechanism connected to the drive shaft and a device able to push against the gas pedal was patented in 1950.[2] He added a speed lock capability that would maintain the car's speed until the driver tapped the brake pedal or turned off the system.[2]