Since it's been available for a couple of years now, we're all pretty familiar with the Audi S4: 340-hp put through all the wheels and controlled with a six-speed box. The C55 is MB's replacement for the C32 AMG— in accordance with their movement away from supercharged engines, MB has bounced the C32's 3.2 liter V6 in favor of a 5.4 liter V8. Review-wise, there are two sides to weigh, since R&T gets all judgemental in terms of both raw data and subjective driving experience. On the strict performance tip, the C55 outperforms the S4 in every category, from 0-60 right on down to fuel economy. But the S4 takes the subjective race, albeit by less of a margin. It's simply more engaging to drive. Potential deal breakers could be the C55's auto transmission, and its price, just over $60K, $10,000 more than the S4. Sure, $60K buys a lot of car, but if it was my money, I'd be in the S4 just so I could get the manual, not to mention the all-weather versatility. R&T, however, feels a bit differently.