SEE IF THE M5 BEATS THE CADILLAC CTS-V: http://www.edmunds.com/insideline/do/Drives/Comparos/articleId=136636 Once you get your hands on a supercharged 556-horsepower 2009 Cadillac CTS-V, you know that you need a 500-hp 2008 BMW M5 with which to measure it. It's a matter of practical science. Of course, there's a sizable price difference between the $59,995 CTS-V and the $86,675 M5, and we don't want to get our comparison results skewed by mere money. Maybe we should add the 507-hp 2009 Mercedes-Benz E63 AMG to our science project. Trouble is, this Merc's $86,875 price tag still doesn't put the CTS-V under any pressure. We had a better idea. We opted for the more nimble 2009 Mercedes-Benz C63 AMG. This compact sedan cranks out only 451 hp, but it weighs almost 400 pounds less than the E63, and its base price of $58,075 rings up about $2,000 cheaper than the CTS-V. Is the 2009 Cadillac CTS-V a true benchmark in the super sedan category? Measured against the pure performance of the 2008 BMW M5 and the value of the 2009 Mercedes-Benz C63 AMG, we knew the truth would come out.