SAN FRANCISCO—When Tesla Inc. posts third-quarter results on Oct. 23, Chief Executive Elon Musk may show off a long-promised quarterly profit, as production of his Model 3 electric sedan takes off. But the real question is whether any such gains will be sustainable.
Since May, Musk has promised that the company will post quarterly profits in the second half of this year as it gains traction with production, and deliveries, of its new Model 3 sedan.
