It depends on the color. If it is tan -- you will know when it is time to clean and condition them. If they are black, than visually they will require less care, but you still want to clean and condition them.
My previous car was Audi A4 and as you probably know Audi people are nuts about detailing and modifying their cars including me (but not to the extend some of the guys I knew did). So, if I may suggest a link to my "old forum" where you can get tons of info on the car care. Plus a lot of stuff they talk about could be applied to any car, not just Audis.
Go to http://www.audiworld.com You can select A4 (B6 platform) forum than select Auto Detailing Forum from a dropdown box. You will find pages and pages with discussion about pain care, leather care, vendors websites, etc.