In August, after Tesla got production underway for the Model 3 and made first deliveries of the new mass-market electric sedan to employees, CEO Elon Musk said there should “absolutely” be “zero concern” about the automaker’s ability to increase production to 10,000 cars per week at some point in 2018. This week, that confidence vanished. During a conference call on Wednesday, Musk was asked if Tesla still expects to hit that target of 10,000 Model 3s per week in 2018. The question was met by a wall of silence for more than 10 seconds. Having acknowledged a production bottleneck of the Model 3 last month, Musk is now warning of a months-long delay, pushing a goal of making 5,000 Model 3s per week back to late in the first quarter of 2018. When that happens, Tesla said, it’ll implement a “capacity addition” to increase the run rate to 10,000 per week. How long that add-on will take isn’t clear, turning the previously-“zero-concern” target i...