Waymo won't launch a public self-driving car service this year, the company admitted Wednesday. Instead, the self-driving provider will offer a small-scale service in Phoenix, Arizona to existing volunteers that have already been screened. The limited service, called Waymo One, is a step toward providing a full service to the general public.

Waymo One will be offered only to users that the company has screened and invited. For months, the Google-Alphabet self-driving car subsidiary said it would launch a public ride-hailing service with its autonomous cars by the end of 2018. Instead, Waymo One will require invited users from its early rider program to download an app and add a credit card to pay for their rides. Reuters reported Wednesday that the cost for trips should rival ride-sharing companies such as Lyft and Uber. A 15-minute, three-mile ride will cost $7.59 compared to a $7.22 ride in a Lyft.

Reuters also climbed aboard the self-driving car for a trial run of the service and found the vehicle "slow and jerky at times." It raised questions of whether invited riders will continue to use the service after the novelty wears off. Waymo will also still have a human driver onboard to intervene in case of an emergency. The self-driving cars will be restricted to a 100-square-mile area in metro Phoenix, covering the suburbs of Chandler, Tempe, Mesa, and Gilbert.

Despite the small scale, it puts Waymo one step ahead in a critical area of self-driving car development: the company can earn money from driver-less cars. Companies and automakers are eager to launch paid services to recoup billions of dollars in investment over the past few years. Key rivals include General Motors and its Cruise subsidiary, as well as Daimler and Uber. GM plans to launch its own public self-driving ride-hail service sometime in 2019.