Fiat Chrysler has signed an agreement to supply "thousands" of Chrysler Pacifica Hybrid minivans to Waymo to support the launch of the company's driverless ride-hailing service.

FCA previously delivered 100 Pacifica Hybrid minivans, adapted for self-driving, to Waymo during the second half of 2016 and an additional 500 in 2017. This collaboration between Waymo and FCA engineers enabled the teams to design a self-driving vehicle built on a mass production platform.

Waymo is set to open its autonomous ride-hailing service to the public beginning in Phoenix this year. The additional Pacifica Hybrid minivans will be used to support Waymo as it expands its service to more cities across the United States. Waymo has officially tested its technology in 25 cities across the U.S., including Atlanta, San Francisco, Metro Detroit, Phoenix and Kirkland, Washington.

Last November, Waymo began test-driving a fleet of Chrysler Pacifica Hybrid minivans on public roads without a driver at the wheel. The hybrid minivans became the first vehicle to attain Level 4 autonomy, a classification determined by the Society of Automotive Engineers.

The self-driving Chrysler Pacifica Hybrid minivans are equipped with Waymo's hardware suite. The self-driving minivans are also running Waymo's self-driving software, which has been honed with more than 4 million miles of on-road testing, and billions of miles in simulation.