How does Autopilot work?

Autopilot allows the car to steer, accelerate, and brake within its lane. It uses the car's eight cameras, 12 ultrasonic sensors, radar, and onboard computer to read lane paint on the road and detect surrounding cars. The hardware that makes up Tesla's self-driving system includes a forward radar, a forward-looking camera, a high-precision digitally-controlled electric assist braking system, and 12 long-range ultrasonic sensors placed around the car. These ultrasonic sensors are strategically placed around the car so that they can sense 16 feet around the car in every direction, at any speed. The radar enables detection of cars and other moving objects. The forward-facing camera is located on the top windshield. A computer inside the camera helps the car understand what obstacles are ahead of the car.

Buyers who pay for Full Self-Driving also get an additional functionality called Navigate on Autopilot, which makes automatic lane changes around slower traffic on the highway, and can steer itself through highway interchanges.