3.1.5 explain radar headway sensor

§A radar sensor (headway sensor) mounted near the front bumper serves as the eyes for the system.

§Other vehicles travelling within the sensor’s range reflect the radar waves, and the sensor picks up the returning signals

§In short, this sensor track the distance and speed of vehicle ahead. This information is sent to the main ECU to reduce speed or re-accelerate depending on the position and speed of the car in front.