Carbon issues are not supposed to affect the new S4... (Audi supposedly fixed the problem or the FI of the new engine doesn't produce carbon deposits)

However, time will tell of course. I think the 4.2 FSI is going to be the main concern over the next few years. A big "whoops" on Audi's part that they're probably trying to quickly sweep away.

From the small bit of research I did when I was looking at RS4's a month or so ago, it looks like this is pretty serious... I think there are some fixes however. (carbon catch cans? Not sure if that fixes or minimizes the issue...etc).

The new S4 is VERY quick. RS4 territory.... after a bit of searching, my focus switched away from the RS4... which is still an amazing car, but not something I need to deal with right now. I just wanted a fast daily that I didn't have to worry about. I was actually looking back at earlier B6's but a 2010 on the showroom floor caught my eye. So for the price of a used RS4, you can get a new S4. Not a bad trade imo.

http://www.youtube.com/watch?v=irFK8VJ_vDs