ACC uses radar, lasers, cameras, or a combination of any of those items to calculate your surroundings. Its sensors and processors judge what the car in front of you is doing and regulate your car in relation to the one in front of you to maintain a safe distance, braking when they slow down and accelerating when they do, up to the set limit. Soon, LiDAR (Light Detection and Ranging), which is a pulsed laser to create a more comprehensive 3D “map” of the car’s surroundings, will also be used to analyze the car’s surroundings, but no car in America is equipped with LiDAR just yet.