The 2008 Audi A4 is largely unchanged, pending a redesign due in calendar 2008 as a 2009 model. New for 2008 is an RS 4 Cabriolet. Audi's top-selling car line features sedans, Avant wagons, and Cabriolet convertibles. All come in A4 and high-performance S4 trim. There's also a super-performance RS 4 sedan and convertible. A4 2.0T models have a turbocharged 200-hp 2.0-liter 4-cylinder engine. A4 3.2 versions get a 255-hp 3.2-liter V6. S4s and RS 4 have 4.2-liter V8s with 340 and 420 hp, respectively. Audi's quattro all-wheel drive is standard on wagons, 3.2 Cabrio, S4, and RS 4. It's available for other models in place of front-wheel drive. Transmission choices, depending on model, are manual, automatic, and continuously variable automatic (CVT). Sporty S line packages include 18-inch wheels and a firmer, lowered suspension. S4s and RS 4 have unique trim and specific sport suspensions. Cabrios have a power fabric top with a heated glass rear window. Available safety features include ABS, traction control, an antiskid system, front side airbags, rear side airbags, and curtain side airbags. Cabrios come with front side airbags that protect the head and torso and rear support bars designed to pop up automatically in a rollover. A navigation system is optional and includes Audi's MMI control for audio, climate, and other functions.