And plans are already in motion. Volkswagen, which has been working with Aurora for the past six months, aims to launch commercial fleets of self-driving electric vehicles in two to five cities beginning in 2021, VW Group’s chief digital officer Johann Jungwirth told Fortune. These “mobility-as-a-service” fleets—a system VW Group is currently developing—will initially include smaller self-driving vehicles (like the SEDRIC pod unveiled in 2017) that people can hail as well as larger vans. Jungwirth says Aurora’s self-driving tech could be applied to other vehicle platforms as well, including autonomous trucks, delivery vans, even roving mailbox stations.

VW hasn’t identified these initial launch cities, but Jungwirth said some will be in the U.S.

“For me, this is a very big deal; it’s a potential partnership of the century, said Jungwirth, who noted the company’s ultimate goal is for anyone in the world to be able access self-driving vehicles and get to where they need to go with “push of a button.”

VW Group is betting Aurora, which provides the package of software, hardware, and data services that make up the self-driving system, will get it there faster.

Aurora will also work with Hyundai to bring Level 4 self-driving vehicles to market by 2021. Under that partnership, Aurora’s tech will be integrated into Hyundai models, starting with the automaker’s new generation hydrogen fuel-cell vehicle. Testing is expected to begin this year.

Both automakers want to commercialize self-driving vehicles globally.

The separate partnerships announced Thursday are a milestone for Aurora’s founders, Sterling Anderson, Drew Bagnell, and Chris Urmson, all early pioneers of the technology who led autonomous vehicles programs at Google (GOOG), Tesla (TSLA), and Uber (UBER). Urmson led the Google self-driving program until 2016, Anderson was the former head of Tesla’s semi autonomous Autopilot program, and Bagnell helped launch Uber’s efforts in autonomy.

While Volkswagen and Hyundai—with their millions of branded vehicles globally—are well-known, Aurora is far from a household name. The company, based in Palo Alto, Calif. and Pittsburgh, has operated largely in secret since it launched last January.

Aurora provides the “full-stack solution” for self-driving vehicles. This means the company will work with Volkswagen and Hyundai, and possibly other automakers in the future, to design and develop the right package of sensors, software, and data services needed to deploy fully autonomous vehicles. Aurora is focused on Level 4 autonomous systems, and eventually Level 5. Level 4 is a designation by SAE International that means the car takes over all of the driving in certain conditions. In Level 5 autonomy, a vehicle is driverless in any and all circumstances and environments.

Aurora might be tiny by every measure, but these comparative giants are counting on the company to help bring commercial self-driving vehicles to world faster.

“It’s been quite thrilling,” said Urmson, who is CEO of Aurora. In many ways, Urmson is in a similar role as when he led Google’s self-driving project, which spun out to become its own business called Waymo in 2016.

“But it’s quite different when it’s, you know, ‘our company;’ we were able to set the mission independently and attract the talent,” Urmson said. “And the fact that two of the world’s largest auto manufacturers share that vision with us and are willing to place a bet on us to partner with them to move this technology forward is humbling and also kind of exciting.”

Volkswagen will deploy autonomous test vehicles developed with Aurora on public roads in 2018. Aurora has been working to integrate its self-driving system into VW’s vehicle platforms. VW vehicles are already on the road, said Anderson, who is chief product officer. However, Aurora is working on a custom vehicle with Volkswagen that is not quite ready yet, Anderson said, adding those vehicles will also be on the road testing.

The number of test vehicles will grow to “triple digits” in 2019, and “four digits” in 2020, before going into production in 2021, Jungwirth said. Ultimately, the self-driving system could be integrated across VW Group’s many brands, including Volkswagen Passenger Cars, Audi, Bentley, Skoda, and Porsche.