it's a Cadillac.
Cadillac used to only appeal to old people (they were big land yachts, with massive engines that sucked gas like crazy, but didn't accelerate fast)
so then they decided to take tried, true, and award-winning engines primarily from their Chevrolet Corvette Z06 division, and put them into the tried and true CTS chassis. Thus the V-series was born... Cadillac luxury, with performance acceleration.
The CTS-V (400HP), STS-V (469HP supercharged), and XLR-V (443HP supercharged). The CTS-V is set apart from the rest because it was designed and tested on the Nuburgreg (or however it's spelled), so it handles like a European sports car (and i can tell you, after driving it for a few days, that really is true!)
I think it's the car with the most performance out of all of the V series, even though it comes stock with the least HP. It's the only one out of the three that's naturally aspirated, the others are forced induction, so if you put a supercharger on the CTS-V, which many, many people do, you'll be pushing an easy 500+ HP, with no other mods. plus you've got insane handling.