The Audi RS6 was the top of the range performance variant for the Audi A6. The first iteration of the RS6 was based on the C5 Audi A6 and was offered as a Sedan or 'Avant' station wagon. These high performance cars were powered by a twin-turbo 4.2L V8 engine  that sent 444hp to all four wheels. Production of the C5 Audi RS6 lasted until 2004, but the model series would continue in the next generation of A6 as the C6 Audi RS6.