The Mercedes M-class hasn't been on the road a year and already we're seeing the ML63 AMG version. This time, the AMG M-class uses a new 6.2-liter V-8 that makes 503 hp and 465 lb-ft without the aid of supercharging. As a comparison, the old ML55 AMG's now puny-seeming 5.5-liter could muster only 342 hp and 375 lb-ft. Power is sent to all four wheels--40 percent to the front, 60 percent to the rear--via a seven-speed automatic with steering-wheel shift buttons and a choice of three shift modes (Sport, Comfort, and Manual). A 0-to-60-mph time of less than five seconds is promised.