The S4 interior shares its design with the rest of the A4 line, which is to say the days of dark and foreboding German interiors is over. Buyers can choose from a variety of interior treatments called "Atmospheres." Our test S4 had carbon fiber-look accents, which look right at home in this high-performance sedan. Special to the S4 are sport seats with deep side bolsters designed to keep driver and passenger in place during vigorous driving. The seats are multiadjustable and just about everyone should be able to get comfortable. The seats are covered with pearl nappa leather, along with the rear seat, armrest, and door panel inserts. It's available in either a dark onyx or silver or, for no cost, with Alcantara suede inserts in either silver or a striking blue.
Audi paid particular attention to the driver's office, with large round easy-to-read instruments under a blister on the dash. The steering wheel is contoured with thumb grips at the proper nine and three o'clock positions, but the surface is harder and slipperier than we'd like.
The back seat is comfortable, but this is a compact car so rear legroom is more limited than in bigger sedans. Although there are three seatbelts in back, three adults will find shoulder room inadequate. This is a four-grownup car.
Regardless of the ingredients, the proof is in the pudding or, in this case, the magic brew. And magic it is. The S4 idles quietly and smoothly, belying the power that won't be revealed in casual around-town driving either. But yield to the temptation to lay into the throttle and the Audi surges ahead, even with revs as low as 2000 rpm. There's a solid push throughout the rev range, with neither turbo lag nor turbo rush. There's no turbo whistle either, just a muted throaty roar from the V6. Motorheads-who are most likely to buy this car-might actually wish the engine was a bit louder under full throttle. The twin-turbo makes quick work out of passing on a two-lane road and it catapults from corners. Without attention to the speedometer, one could easily become radar fodder. In this case, you'll appreciate that conservative exterior.
Although the S4 is available with a 5-speed Tiptronic automatic, we drove only the 6-speed manual transmission. Some 6-speed gearboxes are difficult to use, but there was no such problem with the S4. The only possible complaint is that the fore-and-aft shift throws are somewhat long. Clutch engagement and disengagement are abrupt, not surprising given the amount of power available. Practice will be required for smooth starts and shifts.
Suspension is pleasantly firm. The S4 has the kind of ride that traditional luxury car buyers would call hard. Indeed, compared to even, say, an A6 2.7 T, with which the S4 shares its engine, the S4 rides much more firmly. Road seams, blemishes and flaws that the A6 would absorb, the S4 telegraphs to the occupants. On an undulating road the S4 feels like a speedboat on a light chop. The low-profile 17-inch tires relay a lot of road noise from coarse pavement, seams and bots dots. The payback comes in the crispness with which the S4 attacks corners. The steering has a nice Germanic weight to its feel, a one-to-one correspondence with the road and very precise. The S4 rotates well; even under power coming out of corners. Where other cars would drift wide through a corner, the S4 will continue to turn. Enthusiasts will want to arrange some track time.
A racetrack would be necessary to fully test the massive brakes on the S4. Earlier Audi performance models were shipped without the Autobahn-ready binders because they thought Americans didn't need them. We were unable to elicit any fade from the four big stoppers even when making repeated stops from high speed. If anything, they improved with a little heat in them. We suspect that even track testing would find these brakes unflappable.
Audi S4 comes as one $37,900 model available with a choice of transmissions: 6-speed manual or, as a no-cost option, 5-speed Tiptronic automatic. All S4s come with Audi's quattro all-wheel-drive system, a 250-horsepower twin-turbo V6, massive 225/45R17 tires and leather upholstery.