Audi is testing out an on-demand car-sharing service in San Francisco that allows customers to order an Audi vehicle through its iPhone app.

Audi plans to introduce the service in other cities in the U.S. in the future, according to the automaker.

Customers can select from a wide range in the vehicle lineup from the A4 sedan to the R8 supercar. Once a car is ordered through the app, it is delivered to them by an Audi concierge who will help the customer familiarize themselves with the particular vehicle. The service requires no membership fee.

Audi on demand vehicles allow users to lock, unlock, and start their reserved rides via the smartphone app (or a physical key card).

Customers can reserve an Audi by the day or for up to 28 days.

The service offers the A5 for as low as about $200 whereas the RS 5 is offered at $440 per day, and the R8 Spyder is offered at charges of about $1,285 per day.

In order to reserve a car, one must become a member. Anyone who is 25 and older with a valid driver's license may use the service. The delivery and pick up hours are from 7 a.m. until 8 p.m.