You could fall asleep and wake up at your destination,” said Mr. Musk, Tesla’s C.E.O., but some experts are skeptical that such cars will be ferrying passengers soon.

At any Tesla event, you have to go in expecting a good amount of smoke and mirrors. This is the company run by Elon Musk, after all — its self-anointed Technoking who’s made a career of overpromising and underdelivering.