For its debut in Nashville, where Waymo has been testing vehicles for several months, Waymo says that Lyft will initially be handling fleet management only, such as vehicle cleaning and maintenance, via the Lyft subsidiary Flexdrive. As Waymo scales up service, riders will eventually be able to use the Lyft app to summon an autonomous vehicle, too, Waymo says, though the company wouldn't specify when riders could expect that to take place.