The ride-sharing service announced a new Green Mode Wednesday, which will allow riders to request a ride specifically in a hybrid or electric vehicle for their ride. The feature is launching first in Seattle, and later in other parts of the country.

The EVs are being made available through Lyft’s Express Drive program. That program allows people that don’t have a vehicle to rent a vehicle with unlimited mileage, standard maintenance, and insurance included and drive for Lyft. Lyft says that as part of the initial launch, unlimited charging will be part of the weekly rate for renting one of the vehicles.

Lyft estimates that the cost of driving an electric vehicle will ultimately be half that of driving a gasoline-powered vehicle on the service.

In 2016, GM announced it would allow Lyft drivers to be among the first to get the company’s Chevrolet Bolt. That car was the first EV to be added to Lyft’s Express Drive program.

Last September, Lyft announced that it had delivered its 1 Billionth ride. That number represented a tremendous amount of growth for the company. In October 2017, six years after its launch, Lyft had only delivered slightly more than 500,000 rides.

Lyft has also recently expanded into other modes of transportation beyond just cars. It recently purchased bike-share company Motivate for about $250 million, and has launched Lyft scooters in several major U.S. cities including Los Angeles, Atlanta, Nashville and Washington, D.C.