Mike Duoba, Chief Engineer at Argonne National Laboratory’s Advanced Powertrain Research Facility, looks on as Geoff Amann completes a driving cycle with All-Electric Tesla Roadster at the lab’s Two-Wheel Dynamometer Lab. Photo U.S. Department of Energy

Deliveries of Tesla’s newest sedan, the Model 3, have been slow to pick up. The reason why wasn’t known at first, but it turns out many of the pieces were being made by hand. Tim Higgins reports:

FREMONT, Calif.โ€”ย Teslaย Inc.ย TSLAย +0.37%ย blamed โ€œproduction bottlenecksโ€ for having made only a fraction of the promised 1,500 Model 3s, the $35,000 sedan designed to propel the luxury electric-car maker into the mainstream.

Unknown to analysts, investors and the hundreds of thousands of customers who signed up to buy it, as recently as early September major portions of the Model 3 were still being banged out by hand, away from the automated production line, according to people familiar with the matter.

While the carโ€™s production began in early July, the advanced assembly line Tesla has boasted of building still wasnโ€™t fully ready as of a few weeks ago, the people said. Teslaโ€™s factory workers had been piecing together parts of the cars in a special area while the company feverishly worked to finish the machinery designed to produce Model 3โ€™s at a rate of thousands a week, the people said.

Automotive experts say it is unusual to be building large parts of a car by hand during production. โ€œThatโ€™s not how mass production vehicles are made,โ€ said Dennis Virag, a manufacturing consultant who has worked in the automotive industry for 40 years. โ€œThatโ€™s horse-and-carriage type manufacturing. Thatโ€™s not todayโ€™s automotive world.โ€

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