WOLFSBURG, Germany—Volkswagen Group plans to automate 20 to 30 percent of production at its new Trinity assembly plant under construction here.

“Assembly is still 90 percent manual work,” says Sebastian Schmickartz, the plant’s chief production officer. “This is what we want to change with the new factory. We are looking at 20 to 30 percent automation.”

The Trinity plant, where the automaker will build a new flagship electric sedan, is due to begin pre-series production in 2025, with the official start of production in 2026.

The key to automating more of its assembly line will be moving to a module-based strategy, Schmickartz says, condensing 50 parts into one through techniques like die casting to produce front-end, back-end and roof modules.

The casting technique was popularized by Tesla as an alternative to the more labor-intensive method of assembling multiple stamped metal panels with crumple zones to absorb energy during a crash.