In terms of insane sports sedans, Audi's RS6 sedan would have to rank around the top of the list. Unfortunately, those of us in the United States aren't able to experience it. Instead, we get the more sedate S6 model that packs 435 horsepower from its V-10 versus 580 (!) hp for the RS6. As if it weren't exclusive enough, Audi has announced two new, limited-edition packages for the RS6. The packages are dubbed Sport (now seriously Audi, a sport RS6?!) and Audi exclusive. They are restricted to just 500 examples of each. The models have a top speed of 188 mph and feature a Carbon design package for the engine compartment, 20-inch wheels, and sports suspension plus (again, as if they weren't already!)  Each will have