Audi of America plans to roll out a national car-sharing fleet service for executives next year and has begun testing the service in North Carolina, according Audi.

Known as Audi Shared Fleet, the service will provide cars that users can book and unlock using a smartphone app. Audi has begun a pilot program by offering three red A4 sedans to tenants of American Underground, a technology incubator in Durham, N.C. with more than 200 companies.

The service is being supported by an around-the-clock customer service call center.

In 2015, the company launched Audi on Demand, a smartphone-based daily rental service in San Francisco.