Tesla's "Giga Factory" in Shanghai is its largest and most productive plant, making Model 3s, Ys, and stationary power storage products. Most investors likely haven't been inside. Barclays analyst Dan Levy has.

He recently toured the Shanghai plant, offering a unique look inside an important facility. "Giga Shanghai is a key source of volume and margin strength for Tesla... accounting for more than half of Tesla's global auto production," said Levy. "Vehicles made at Giga Shanghai offer substantially better cost. And with exports now tracking at nearly half of Giga Shanghai production, we are seeing the benefits of Giga Shanghai supporting both increased volume and margin."

Chinese auto makers have labor cost advantages over their Western counterparts, an advantage they have used in export markets. That reality has impacted Tesla's local approach to automation.

"At Shanghai, we saw more manual labor than we expected. Indeed, while Shanghai is heavily automated, it nevertheless employs relatively less automation than [Tesla factories in] Austin and Berlin," said Levy. "The approach at Shanghai reflects Tesla's push on automation balanced with pragmatism."

One example: the rears of Shanghai-made cars are 'gigacast,' which essentially means using liquid aluminum to create a single part, eliminating multiple parts and joints. Tesla's Berlin factory gigacasts the front and rear of cars. Parts stamping and car painting at Shanghai are fully automated. Most welding is automated. Levy saw more manual labor in final assembly.

(Making a car, of course, is a complicated multi-stage process. Parts are stamped, welded, and painted, then eventually married with a power train before finishing everything.)

Tesla's Shanghai plant is an impressive operation, and one of the world's largest manufacturing facilities. Oddly, EVs aren't really driving Tesla stock these days. Investors are focused on Tesla's AI efforts, including robo-taxis and robots.

Tesla's manufacturing still matters, though. For starters, Tesla's EV business helps fund AI efforts. Second, Tesla plans to make a lot of robots. Low costs and innovative approaches will help the company compete with others, including Chinese robot makers.

Tesla stock was up 0.5% in premarket trading at $368.60, after climbing 2.3% Thursday. S&P 500 and Dow Jones Industrial Average futures were 0.1% higher and 0.1% lower, respectively.