I have been thinking about putting the ol' Lude out to pasture and have been researching both these cars. I really love the S4 (My friend just got his.). It's fast and after chipped is a screamer. However, I also like the IS300. It's a nice looking car. If you had to pick one, which one and why? I'm leaning towards the S4 for it's power, quattro, and it does really well at the SCCA events here (ala Corey Smith). However, not sure if I want to spend the extra 10K if I could get the IS300 and still have a quick and nimble car.