Marcus Leng, the chief executive of Openers, at the company’s headquarters in central California on May 19,2021. For years, people like Leng have kept their prototypes hidden from the rest of the world, but they are now beginning to lift the curtain. (Jason Henry/The New York Times)

What is a flying car?

For years, people like Openers CEO Leng have kept their prototypes hidden, but they are now beginning to lift the curtain