The beta programme allows users to book an Audi for between one and 28 days via a smartphone app. Users can book a variety of vehicles from the A4 up to the R8, as well as specify options, such as child seats, ski or bike racks.
A concierge will deliver the specified car at any nominated time between 7am and 8pm local time. First time users of the service need to be verified by the concierge and be run through a 20 minute introduction to company's electronic and infotainment systems.
Subsequent to this, delivery and pick up can be arranged from any publicly accessible parking spot, with the car unlocked via the smartphone app.
At the moment, the service is only available within the 127 square kilometre area that's legally defined as the city of San Francisco.
In addition to the geographical limit, there are a number of caveats with the present Audi on Demand service. For example, the Audi on Demand app is currently only available for iPhone users, participants are only allowed to book one car at a time, and no additional drivers are permitted.
The beta programme is open to anyone over the age of 25 with valid driver's licence and credit card. Bookings can be arranged between two hours and six months prior to delivery time. Model availability may limited for last minute bookings.
According to the service's website, 10 vehicles are currently available via Audi on Demand: A4 Allroad (US$165 / $214), A5 (US$200 / $259), A6 (US$200 / $259), Q5 (US$200 / $259), S5 Cabriolet (US$300 / $389), S7 (US$385 / $499), A8L (US$425 / $534), RS5 (US$550 / $714), R8 (US$1195 / $1550) and R8 Spyder (US$1285 / $1666).
Audi says that all the cars available via this service will feature all-wheel drive, satellite navigation and satellite radio as standard.
The company says that Audi on Demand will "be rolled out across additional US cities in the coming years", and that it will also soon launch a micro-sharing service, dubbed Audi at Home.