This car has a staggering degree of grip. I found a parkway outside of Los Angeles and I started doing laps around the breaks in the medians. The length was about two city blocks and the surface was uneven pavement. With each lap I increased the speed and the car felt more and more like it was literally digging into the pavement, the tires seeking out the last possible millimeter to which they could apply adhesion. I have never experienced this kind of feeling before. It was exciting, confidence-inspiring. At the limit, the rear of the car began to push, but hammering the accelerator to the floor pulled it back nicely. The engine has power on demand and feels like a V8; I didn't notice any turbo lag whatsoever. The car is nicely balanced and has a very "smart" feeling suspension. I could swear the suspension was self-adapting to the speed and G forces.
The interior of the car is very tasteful and understated, much in the tradition of Audi. This particular car had the Alcantra inserts which provided a firm, grippy ride. The steering wheel was precise and beefy, very assuring when cornering at high speeds, but I wished for slightly less power-assist. My only other complaint was with the exhaust note; I wished it was louder. Perhaps the interior was so well insulated I didn't notice. Maybe this last thought is on the money because I thought all along that Audi was trying to make a more civilized, comfortable, versatile car than the BMW M3. Personally I loved this car and where I live, M3s are literally everywhere. S4s are much rarer and therefore cooler. They don't attract the attention of every cop on the street and are quiet enough to blast down city streets in a stealth-like manner. If you don't need to brag to everyone that you bought a BMW, I think this is the car to beat at $40,000.