Hands-free autonomous driving is no longer the stuff of Silicon Valley dreams and bug-eyed research vehicles. With Cadillac’s long-awaited Super Cruise feature, which launches this month in the 2018 CT6, drivers will be able to buy a car that can drive itself on many highways. Unlike existing semi-autonomous driver-assistance systems from Tesla, Mercedes-Benz, BMW, and Volvo, you don’t have to keep a hand on the wheel or retake control of the car after a few seconds. Super Cruise is designed to drive the car by itself for hours on end without driver intervention. 
Of course, there are limitations. General Motors describes Super Cruise as a Level 2 autonomous system, one in which the system can handle steering, acceleration, and braking while operational. While it doesn?t require a frequent hand on the wheel, it does require human monitoring. So far it works on the 130,000 miles of highways in the United States and Canada that Cadillac has specially mapped (including those that a caravan of CT6s are currently using in a cross-country journey showcasing the technology). Super Cruise works only on divided highways that have no intersections, and it cannot perform sophisticated maneuvers such as changing lanes. It will not work above 85 mph or in a snowstorm, and it can behave like a peeved parent. If you start horsing around behind the wheel?turning away too much to interact with your passenger or watch a movie?it will stop the car.

A steering-wheel light bar ...