Audi knows how to bring the pain to the competition by producing a line of high-performance sedans and coupes to rival the best from BMW, Mercedes and Infiniti. The 2009 Audi S6 is a prime example. Not as smooth on the highway as the more mainstream A6 on which it's based, and not as quick through a canyon as a similarly-priced Porsche 911 Carrera, Audi's factory-tuned S6 – like most of Germany's factory-tuned super sedans – is nonetheless a brilliant way to enjoy varying degrees of each with only a single monthly payment. Now if we could just convince Audi to build a wagon model like the S4 Avant.