The A4 is Audi's spirited and versatile mainstay, offering a combination of style and substance that keeps it highly competitive within its class. It is available in either a sedan or wagon (Avant) body style, both with Audi's legendary quattro all-wheel drive system; FrontTrak front-wheel drive is also offered on the sedan.

The A4 is outfitted with a 211-hp 2.0-liter turbocharged four-cylinder engine, featuring FSI direct fuel injection; available transmissions include a six-speed manual, a six-speed automatic with Tiptronic manual shift mode, and a Multitronic CVT. Every A4 is equipped with the Premium package, including a power sunroof, 17-inch alloy wheels, leather upholstery, automatic climate control, satellite radio and an auxiliary input jack. A Premium Plus package, available for all variants, adds features such as Xenon Plus headlights, LED tail lamps, heated front seats, three-zone climate control, Homelink universal garage door opener, Bluetooth wireless connectivity and an Audi Music Interface with iPod integration. The quattro models can be further equipped with a Prestige package that boasts 18-inch alloy wheels, Advanced Key passive entry/start, voice-activated navigation, DVD player and a Bang & Olufsen premium sound system. Standard safety features include electronic stability and traction control systems, four-wheel anti-lock disc brakes with brake assist, front side-impact airbags, overhead curtain airbags for front and rear passengers, and a tire pressure monitor; rear side-impact airbags are optional.

Following an extensive redesign last model year, the Audi A4 carries over with minimal changes for 2010. A new Driver Assist package, including blind spot sensor and rear backup camera, is available for quattro models. Additionally, the Cabriolet body style has been discontinued.