2007 Audi S8 front

Audi will soon go where BMW dares not tread: into the ring with the AMG-enhanced Mercedes S-class. It helps to have standard all-wheel-drive and an aluminum body; access to a 450-horsepower Lamborghini V10 doesn't hurt either. Put the two together and you've got one roomy, powerful, all-weather (and likely six-figure) ultra-luxury sedan.