Low, sleek, and powerful, the Audi S4 receives an exterior refresh for 2009, with new front and rear S-type bumpers, a subtle rear spoiler, and four exhaust tailpipes (dual pipes on either side). Other exterior design cues include the distinctive Audi deep-mouthed grille with vertical chrome bars, eyebrow-shaped bi-xenon high-intensity headlights, and high-performance tires with S-style five-spoke wheels. As with any Audi S-trim, however, the real story resides under the long, stylish hood, and for 2009 Audi S4 power will come in the form of a new supercharged 3.0-liter V6 that produces 350 horsepower and drives the S4 from 0 to 60 in under 6 seconds. This lighter engine will help improve the S4's performance, although the V6 will link to a new, heavier S-Tronic dual-clutch transmission capable of making shifts in 200 milliseconds - quicker than any human could. The new transmission will also help reduce the car's carbon dioxide emissions. By positioning the transmission low and centrally in the car's frame, Audi will minimize the effects of its additional weight. As in previous years, the 2009 S4 will feature the quattro all-wheel-drive system, providing additional stability and traction. The S4 rides on a sport-tuned suspension with gas-charged shock absorbers, designed for aggressive cornering and responsive handling. The S4's interior has always been class-leading, and the 2009 version of the S4 will be no different. New features include standard Bluetooth hands-free communication and Sirius satellite radio. Other standard features include Recaro sport seats with Nappa leather, headguard airbags for front and rear passengers, a power tilt-and-slide sunroof, wood interior inlays, dual-zone climate controls, an Audi symphony audio system, and a backlit instrument cluster. Audi includes antilock disc brakes, electronic brakeforce distribution, brake assist, stability control, and a tire-pressure monitor system as standard safety equipment. In addition, the S4 has received top ratings in frontal- and side-impact tests.