With 500 horsepower on tap, the 2006 BMW M6 is the mac daddy of the 6 Series line. The “basic” version offers only 360 horsepower and can be configured as a coupe or convertible, and sells for about $72,000 to $79,000, plus options. The M6 is available only as a four-passenger coupe and starts at just under $97,000. For you math freaks, that translates to $194 per horse, but like the living and breathing kind, these ponies might run you dry on feed, especially if you run ‘em hard.