Originally Posted by mdosu
i like your thought. I thought the carbon buildup on the 4.2 was fixed by Audi in the current generation of S5?
Prior to the switch to the supercharged V6, the 4.2 V8 in the S5 definitely had carbon build-up issues. The image below comes from this thread
. You can read more about the whole issue here
Maybe Audi has finally addressed the issue, but the engine is just a slightly modified version of what you'll find in the old RS4 and V8 R8 and I doubt there's much they can change at this point. The problem isn't insurmountable; the build-up can be removed. It's just something you'd have to be aware of and eventually deal with. Obviously it's not a huge issue if you choose to lease an RS5.