Mercedes-Benz relies on big displacement to take on the 2008 BMW M3 Coupe, in the form of a normally-aspirated 6.2-liter V8 engine whipping up 475 horsepower. It needs an engine that big to move the 2007 Mercedes-Benz CLK63 AMG’s 4,150-pound curb weight to 60 mph in an estimated 4.6 seconds. Offered only as a convertible, the CLK63 AMG actually sits between the new M3 and the larger M6, priced in the mid-$80,000 range. Mercedes offered a less expensive alternative in the C55 AMG sedan for 2006, but that car has been discontinued for 2007 and beyond.