It’s now clear why Hertz is buying a so many Tesla cars. The company is making up to 50,000 Tesla EVs available for rent solely to Uber ridesharing drivers in the US starting on November 1st. Workers in Los Angeles, San Diego, San Francisco and Washington, DC will have the option of paying $334 per week (eventually dropping to $299 “or lower”) for a package that includes a Model 3, insurance and maintenance.

Drivers will initially need at least a 4.7-star rating and 150 trips to be eligible. The program will expand across the country in the “following weeks.”

The company saw the Hertz deal as helpful for both the environment and, potentially, drivers’ bank accounts. It should reduce vehicle emissions and expose many people to EVs for the first time, Uber said. However, it could also lower some running costs. Drivers won’t have to pay for fuel, after all, and Uber has incentive programs that offer more money per trip (up to $1.50, if it’s an Uber Green ride) to EV operators.

Uber has strong motivations to adopt EVs. They could help the company reach its goal of zero emissions by 2040, and may tackle complaints that ridesharing makes CO2 emissions worse. The firm could burnish its image with eco-friendly cars roaming the streets. Even so, it’s a big deal both for curbing car-based emissions and for EV adoption — 50,000 cars is a large chunk of Tesla’s production, and likely one of the largest single-customer EV purchases to date.