More than a year after General Motors Co. submitted exemption requests for its fully autonomous vehicles to drive on U.S. roads, the National Highway Traffic Safety Administration has issued a 60-day public comment period over the proposition.

GM is proposing exemptions from a few federal motor vehicle safety standards for a fully autonomous and zero-emission car fleet that lacks steering wheels, manual transmissions and foot pedals for braking or accelerating.  Experts said that while the request represents an advancement of driverless cars, there is still a long way to go—and many legal issues to consider—before such technology hits the road.