Power for the S4 is provided by a 3.0-liter six-cylinder, using supercharging, intercooling, and direct injection to boost its output to 333 horsepower and 325 pound-feet of torque. With a grittier sound than the old, sweet Audi V-8 purr, the six shifts its power to the ground through a six-speed manual gearbox or our editors' favorite, a seven-speed dual-clutch transmission with paddle shifters that clicks off quick, precise, clutch-pedal-free gearchanges. Audi says the S4 shoots past 60 mph in 4.9 seconds, with a limited 155-mph top speed. It's as fast as a BMW M3 or a Benz C63. Fuel economy is actually quite good—it's rated at an awesome 18/27 mpg for manual-equipped S4s, and 18/28 mpg for the dual-clutch edition.
Just as the A4, the S4 gets Audi's quattro all-wheel drive, with a power split weighted to the rear wheels, and an optional Sports Rear Differential that vectors power from side to side, give the S4 awesome road-holding potential and grippy feel. It's entertaining to press to its tire limits, but the S4's optional Drive Select system dials in lots of artificial heft to the electronic power steering, while giving the driver some usable flexibility in ride comfort and transmission response. Audi's base configuration works well enough to avoid the expensive option.
The S4 shares most of its body with the Audi A4 sedan, but gets a number of more aggressive and distinctive details, including LED daytime running lights, capped by LED tail lamps, along with deeper front and rear bumpers, a revised grille, new side moldings, a small spoiler on the trunk lid, bright mirror housings and bright trim on the air diffusers in the bumpers, and 18-inch wheels. Inside, the S4 has a taller, darker dash that's not as classically handsome as previous Audi interior themes, but it's still an efficient place to work. Special S4 additions to the basic wide-binnacle dash include a black headliner, a new steering wheel, aluminum trim, and a choice of console and door trim: walnut, aluminum, gray birch, or woven stainless steel.
The cabin and cargo holds of the 2011 Audi S4 are essentially identical to the A4 sedan; but the S4 does get unique front sport seats with firm backrests and high headrests that sit at an ideal angle. As with the A4, quality materials are incorporated throughout, though some knobs could look nicer and work with more refinement.
With top-notch ratings, a Top Safety Pick designation from the IIHS, and available rear-thorax airbags, the S4 doesn't miss any major marks for safety. It's heavily equipped with technology and luxury features, too. Leather is standard, along with Bluetooth, a music interface for audio players, keyless entry and ignition, xenon headlamps, and Audi's MMI controller, which operates audio, climate, and navigation functions. A navigation system is an option on the S4, along with adaptive cruise control, a blind-spot warning system, and a 505-watt Bang & Olufsen audio system.
For full details on the rest of the package in the Audi A4 and S4—including up-close descriptions of styling, interior accommodations, safety, and features—see our full review on the 2011 Audi A4 Avant and A4 sedan.