Uber is getting a $500 million investment from Toyota, and putting its self-driving technology into Sienna minivans, which will be installed in its fleet. The new autonomous cars, first reported by The Wall Street Journal, won't even hit the roads until 2021.

In another turn, the new fleet of mini-vans won't be run by Toyota or by the ride-sharing service, but "will be owned and operated by an agreed upon third party, a new business model," said Uber in a statement.

Called an "Autono-MaaS' fleet — or autonomous mobility as a service — the minivans will be available to Uber riders through its ride-sharing network.

Toyota and Uber forged a partnership in 2016, at the time looking at how the two could work together on ride-sharing platforms.

The carmaker had also, at one time, considered buying Uber's autonomous technology – until a fatality in Tempe, AZ. involving one of its test cars saw Uber shut down testing of its self-driving project. Others followed including Toyota, which suspended its own self-driving car tests after Uber's accident in March.

Carmakers have been investing in self-driving technology for the past few years. Ford launched a partnership with Lyft in 2017 to build self-driving cars for the ride-sharing's network. Waymo is working with Fiat Chrysler, with plans to add the carmaker's Chrysler Pacifica minivans to its fleet after ordering 62,000 of them in June.

The $500 million investment from Toyota is said to be separate from the partnership to roll-out self-driving Sienna minivans to Uber's network. The size of the deal, however, is significant and gives Uber serious backing, and a longer runway for its self-driving goals.

"The deal is the first of its kind for Uber, and signals our commitment to bringing world-class technologies to the Uber network," said Dara Khosrowshahi, Uber's CEO. "Our goal is to deploy the world's safest self-driving cars on the Uber network, and this agreement is another significant step towards making that a reality."