Look into the lemon law like ^^^ said. Make sure you are using the oversized oil filter, it's been updated. I think there was something about the oil sludge screen on the A4's also. I recommend joining audizine.com and audiforums.com for more answers. The coilpacks are a common problem and depending on how many mile the car has, you might not be able to get it warrantied. Do you have tweets and mids on all 4 doors? If you are looking for a set of OEM bose, I may be able to sell you mine for cheap. Another common problem is the speaker wiring for the doors become sh!t and you'll have to replace/re-route them. I think one of mine is going out too. These are some of the things I picked up while researching the Audi A4's. I have a 2002 but mine is the new (B6) body style. Hope this helps.