Drivers always mention how fun it is to sit behind the wheel of the Audi S4, listening to the powerful engine as they blow by comparable cars on the highway. What's even better, they say, is the S4 takes people by surprise, because it looks like the A4, on which it is based. This high-end classically styled family car appears unassuming, until you step on the gas pedal. Available as either a sedan, Avant wagon, or Cabriolet convertible, all 2006 Audi S4s come with a 4.2-liter, 340-hp V8 engine with standard 6-speed manual or optional auto/manual Tiptronic transmission. Of course, all feature Audi's quattro all-wheel drive system, which outstrips SUVs for its handling and control in any road or weather condition. Recently revised in late 2005, a new 40/60 front/rear torque split quattro was added to manual S4s. The greater torque in the rear means a little bit sportier ride. Automatic S4s maintain the old 50/50 quattro. In 2006, the Audi S4 celebrates 25 years of the innovative and still unsurpassed quattro technology by releasing an S4 25quattro. This limited edition model features silver paint, special 15-spoke 18-inch wheels, badging, rocker panels, and carbon-fiber bumper trim. Also new in the 2006 S4 is brushed aluminum trim on the interior, new performance tires, and some V8 badging. Drivers love the power and handling of the 2006 S4, saying it offers precise steering and tight cornering capabilities. Many prefer it to the comparable BMW M3 in terms of luxury features and functional interior. Quattro AWD is great in snowy climates, turning this sports sedan into a practical all-weather car. Drivers also mention the comfortably supportive Recaro sports seats, the smooth ride, responsive acceleration, and large trunk capacity. The exhaust sound is satisfyingly thrilliing. Complaints range from high gas consumption, to a cramped backseat, some rattling noise over bumps, and poor cupholder location. The Bluetooth capability doesn't always work, and only some phones are compatible. Drivers also feel the S4 is too heavy to ultimately benefit from the V8 engine.