Bill Alpert:

Tesla doubters have been wrong on more than the stock. The Palo Alto, Calif., auto maker delivered almost 22,500 Model S sedans in 2013, more than $2 billion worth, to surpass North American sales of comparably priced Audis and Porsches. So when Musk says that he’ll lop 30% off battery costs with a “Gigafactory,” the world pays heed. Four states are bidding for the plant, which by 2020 would exceed the lithium-battery production of all the world’s current factories combined. “The scale of what he’s talking about is outside of what’s been discussed by anybody in my 20 years in the business,” says Menahem Anderman, whose Oregon House, Calif., firm, Total Battery Consulting, runs international conferences on battery technology. “But maybe that’s what it takes to start up an electric-vehicle business.”

Could the Gigafactory bend the lithium battery’s stiff cost curve? Tesla hasn’t responded to Barron’s queries since Musk hung up on us in an interview last spring. However, battery veterans agree that such a factory might achieve the promised economies—but only if Tesla can sell the half-million cars per year that would keep the plant running at capacity. Tesla’s stock price seems to take 500,000 sales for granted. Sales of battery-powered cars will hopefully increase in coming years—last year they totaled about 100,000 worldwide. And, by the time Tesla delivers the thrifty Gen III car in three or four years,competitive products will appear from worthy rivals like BMW (BMW.Germany), with lithium batteries from Samsung SDI (006400.Korea) and LG Chem (051910.Korea).

Investors needn’t wait until 2020 to handicap Musk’s chances. In the next few months, we’ll know whether Tesla finds partners for the $4 billion to $5 billion project. Questions about the Gigafactory figured prominently at a Thursday news conference in Tokyo by Tesla battery supplier Panasonic (6752.Japan). Although it is expanding production in Japan to meet Tesla’s rising orders, while shedding some consumer businesses, the electronics giant only just returned to profitability. Panasonic tells Barron’s that it hasn’t decided whether to invest in the costly Gigafactory.

Wall Street and Telsa’s auto-industry rivals will watch to see how strong sales are this year for the Model S, and next year for the Model X, a crossover that may be a bit pricier. Tesla expects to deliver more than 35,000 cars this year, as it tests new markets in Europe and Asia. North America took almost 19,000 of the sporty sedans last year. Although Tesla doesn’t report monthly sales, the market researchers at Malvern, Pa.-based Auto Outlook count new Tesla registrations. In 2013’s second half, the monthly tally showed Tesla sales to be flat at best in key markets like California. In its year-end conference call, Tesla said that it is delaying North American deliveries to supply cars to Europe—leading some observers to expect noticeably longer waiting times in North America. But a team of buy-side researchers tells Barron’s that its survey of Tesla sales locations finds wait times unchanged from last year—puzzling if demand is unabated.

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TESLA SHARES SPIKED from $217 to $265 in late February, after Morgan Stanley analyst Adam Jonas wrote that the Gigafactory plan increased his valuation from $153 to $320. Two days later, with the shares at $252, his investment-banking colleagues helped Tesla sell $2 billion in convertible debt. The Morgan Stanley report was light on economic details