The Audi A6 Handbook includes a supplement, Symphony and OE Assistance Number Cards for owners of the C5 facelift models. Produced by Audi, the manual is a valuable resource for car enthusiasts looking to understand their vehicle better. The handbook provides essential information and maintenance guidelines specific to the A6 model, making it a must-have for owners seeking to keep their Audi in top condition. With detailed instructions and insights, this handbook is a practical tool for Audi A6 owners.