Advanced as it appears to be, the system cannot be considered in any way “driverless.” The human driver remains responsible for the operation of the car — functionally, and legally. Super Cruise includes a tiny camera that tracks eye and head movement to make sure the driver is paying attention to the road, ready to take control if needed. Look away from the windshield too long — 10 seconds or so — and the car will flash warnings and sound alarms with increasing urgency, and eventually ease to a stop if no action’s taken.

Tesla Autopilot and systems from Mercedes-Benz and BMW don’t use head tracking. They require drivers to return hands briefly to the steering wheel for a few moments after a short passage of time to keep automatic steering engaged.