Electric vehicle (EV) maker Rivian (NASDAQ: RIVN) said late Tuesday that it closed a hugely important deal, in which giant Volkswagen (OTC: VWAGY) will invest billions in the California-based upstart.

Rivian and Volkswagen Group have finalized a multi-billion-dollar joint venture to develop software, paving the way to let the German auto giant leverage the EV startup’s more technical chops in the coming years. Volkswagen will invest up to $5.8 billion by 2027, about 16% more than when the deal was first announced in June.

Volkswagen has increased its planned investment in the electric automaker Rivian through a joint venture that officially launches Wednesday. The first Volkswagen models made with Rivian’s technology are expected to launch in 2027.