On July 1, Elon Musk went home to sleep. The chief executive of Tesla Inc. had been camping out at his electric car factory in Fremont, Calif., for much of the past week. He’d been sleeping on a couch, or under a desk, as part of a companywide push to get out of what he calls “production hell” by manufacturing at least 5,000 of Tesla’s new Model 3 sedans in a week. “I was wearing the same clothes for five days,” Musk says in an interview with Bloomberg Businessweek. “My credibility, the credibility of the whole team,” was at stake.