Today, the Audi S4 is a direct threat to the BMW M3. Offered in convertible, sedan, and wagon body styles, the Audi S4 gets a Quattro all-wheel-drive system connected to a 340-horsepower 4.2-liter V8 engine. If that’s not enough, and once the new 2008 BMW M3 arrives it won’t be, select the new Audi RS 4 sedan, which generates 420 horsepower and acceleration to 60 mph in 4.8 seconds. However, the RS 4’s price tag is prohibitive at a starting point of about $69,000.