What does res in the car mean?

Res on the car is the speed at which the cruise control system resumes setting. RES has two functions, one is to accelerate after the cruise, and the other is to press RES to return to the previously set speed after the cruise is temporarily cancelled. The driver chooses the speed according to the road conditions, and starts the cruise control system by inching the switch instead of the accelerator pedal control. According to the influence of ramp and road conditions on the speed, the fuel supply is automatically adjusted, and the vehicle can automatically travel at a constant speed. With this device, the driver does not need to control the accelerator pedal after driving on expressway for a long time, which reduces fatigue, unnecessary speed change and saves fuel.