quattroforum.com
- Forum for owners and enthusiasts.
- http://www.quattroforum.com

Audiport.com
- Enthusiast information related to the Audi S4 and A4.
- http://audiport.com/

High performance cars from Audi
- Information on the S and RS series performance automobiles from Audi. Includes technical details and forums. Site is primarially in German, and seems to have most if not all of the information available in English also.
- http://rsmodels.net/

Audifans.net
- A portal for Audi owners & enthusiasts's. Includes a forum, classified advertisements, photo gallery, news and reviews, and extensive news on Audi Motorsport.
- http://www.audifans.net

AUDIPower.net
- Information on tuning, new models, and concept cars. Also includes photograph gallery, forum, polls, and shopping links.
- http://www.audipower.net

European Car Magazine: Look Back: Audi Cabriolet
- Long term report on the Audi Cabriolet, detail's the vehicles faults and features.
- http://www.europeancarweb.com/lookback/0206ec_audi

Audi Forums
- Discussion board for Audi enthusiasts.
- http://www.audiforums.com

audi-sport.net
- Forums for owners and fans of Audi and VW automobiles. Membership is required to post.
- http://www.audi-sport.net/

DKW, Auto Union & Audi in South Africa
- A wide range of information on DKW, Auto Union and Audi in South Africa.
- http://www.dyna.co.za/cars/dkw.htm

Huw's Audi Garage
- Provides maintenance details, wiring diagrams, and basic "how to" advice.
- http://www.humanspeakers.com/audi/index.html

Audifans
- Maintains the Quattro email list and a number of other forums. Also offers classified ads, links to parts suppliers and mechanics, and searchable archives.
- http://www.audifans.com/

AudiWorld
- Comprehensive collection of Audi news and information. Discussion forums, up-to-date news, current and historical model listings, model FAQ, and product reviews.
- http://www.audiworld.com/