GM's Cadillac Cyclone, the self-driving wonder of 1959. (Reuters)

Tesla’s Elon Musk has already inflicted serious embarrassment on lumbering carmakers with his profitable and much-hailed Model S electric car. But while they are fighting back in the electric-car race, they seem content for Musk to take the lead with the next big technological advance in transportation—the self-driving car.

If that sounds defeatist, so be it. Big carmakers say the legal and cultural hurdles for autonomous autos are so daunting that they’re happy for Musk to take the first leap.

He promised this week that Tesla will be ready with a semi-autonomous car able to handle 90% of the driving within three years. By comparison, General Motors, the world’s second-largest carmaker, says vaguely that it will only begin to sell a semi-autonomous Cadillac outfitted with what it calls “Super Cruise” capability by the end of the decade.

Relying on sensors, radar and GPS, Super Cruise will self-navigate highways as long as there are white lines designating the lanes and they are not covered by snow. If there is a crash, the car will come to a stop, but the driver would still have to steer around it.

“The driver can’t go into the back seat and take a nap,” GM’s Daniel Flores told Quartz. Neither will the GPS allow driving on city streets.