The Audi A6 midsize luxury sedan is perpetually fighting the BMW 5 Series and Mercedes-Benz E-Class. Now in its fifth generation and carrying a base price of $65,000, the A6 can also be ordered as a practical wagon called A6 Allroad, a sporty S6 sedan or a mean and mighty wagon dubbed RS 6 Avant. The last one will blow you away with a turbocharged V8 engine that cranks out 591 horsepower.