Self-driving dilemma: How to pass the wheel between human and robot

Some developers, such as Waymo, the driverless-car unit of Google parent Alphabet Inc., are planning to skip the interim step, convinced there isn’t a reliable way to hand off the wheel. Others are devising semiautonomous vehicles that rely on humans when driving conditions exceed the computer’s abilities.

General Motors Co. GM -0.49% is marketing the new Cadillac CT6 sedan, due out this fall, which lets drivers go hands-free on the highway—but the car also features eye-tracking technology that forces the driver to look at the road or the robot pilot will disengage. Toyota Motor Corp. TM -0.36% has been touting the redesigned Lexus LS sedan that automatically can swerve to avoid pedestrians, but drivers must keep their hands on the wheel.