The days when your car will autonomously pick you up, drive you to a destination and drop you off at the door are many years away, but the building blocks for full autonomy are already on the road. They may even be in your own car in the form of some high-tech safety and convenience features like these.
Adaptive cruise control watches the car in front of you and maintains a gap even if that car slows down or speeds up. Buttons on the steering wheel let you choose how closely you want to follow. The best systems bring you all the way to a stop. To turn it back on again when traffic pulls away, you have to either tap the accelerator or press the resume button on the steering wheel.
Lane departure prevention, often called lane keeping aid or assist, will steer the car back into your lane using a camera that looks at the lane markings ahead of you. Where some of these systems are corrective and jerky, others will keep you centered in the lane without a whole lot of pinballing left and right.
The 2016 Volvo XC90 has a feature called Pilot Assist that combines a couple of these features. It does the steering and the acceleration and braking for you. In this model it works only up until about 30 mph. In the next model year and in a new Volvo sedan, the company says it will work all the way up to highway speeds. Most cars that have any kind of lane-departure prevention require you to take the wheel after a number of seconds. Tesla is an exception already, and in time there will probably be more.