think the real question is, does the audi come with a warranty?
personally, as someone else mentioned, a new car instantly depreciates, so not alot of point in getting one there!
plus id just go for audi anyway... quattro, reliable, nicer looks imo 🙂
Definately go for the A4, personally I think they are a LOT better looking and probably have a far better resale value for when you come to sell it. Check out some prices here http://www.usedaudia4.com
Have you driven either car yet? It's one thing for us to suggest a certain car, but it is another for you to get behind the wheel and get a feel for the vehicle.
How much is the Audi selling for? I've driven a 2008 A3 a few times and loved it. It is one quick car. The A4 is even nicer.