First off, Audi's S4 is an absolute blast to drive. No one realizes just how fast this car is just by looking at it. The 4.2L V8 is an amazing motor. The driving experience doesn't stop at the motor either; the seats are deeply bolstered and I love the extendable thigh support in the seat bottoms. The steering is speed sensitive and tightens as needed for a extremely communicative feel of the road. The all-wheel drive keeps the wheels connected even in rain (or snow I've been told) for a very stable handler. The Audi fit and finish is as expected for a high-end German car: exceptional. The way they use leather and soft plastics is so far ahead of even the Japanese luxury competitors, it's no comparison when it comes to general ergonomics and comfort. Although I still maintain that German's don't quite understand what a fully functional cup holder is (the S4 comes with 3 that can be hidden away in various places like the dash and center console). The other downsides to this beast would have to be the rear seat legroom and gas mileage. The rear seats could use a bit more space if you cart adults around, especially tall ones, but Audi's A4 and S4 are well know for that already. The gas mileage could be better as I've been averaging about 18mpg in mixed city and highway driving but I think that's a fair trade off for just how fun this car is to drive. Overall, I love the thing. It looks great, it drives wonderfully, has great back support, and best of all, I don't look like a racer to the police or other tuner types on the road. Hands down, this is one of the best sleeper performance vehicles around.
Drove an A4 for about several years and never thought I would own an S4, was looking for a Allroad to replace my A4 Avant and my salesperson showed me a S4 that was just traded in. The price was a little below national average and in good condition. There was some cosmetic blemishes all over the car that I found as I washed it but over all its an amazing car. Not super crazy about the MPG's and its a little tight in the cabin but its all about the sharp steering, feeling the engine torque pull you into the seat as you run thru the 7 speed DSG. Not sorry about choosing automatic vs manual transmission either, the sport mode knows when to shift based upon what the driver is doing and if you know what your doing, its a rush to drive.
Great car, handles and performs as I hoped it would. This is a step above the A4 and the ongoing maintenance will reflect that going forward so be ok with that if you buy one.