CTS-V looks nice though Yank motors are a little brash for european tastes.
I've always found these 4 door supercars a bit puzzling. Y 'know, CTS-V, Audi RS4/5/6, M5, top end Evo/STi etc etc ? On face value it's a pratical 4-door but then it has a big-power engine, with big fat tyres and all the associated running costs so it's not really all that pratical.
On the other hand it's a supercar but with none of the drama or awesome shape of a coupe/supercar. So it's neither one thing nor the other.
Personally, I'd have something totally urbane for day to day (Focus, Astra, Corolla etc, something unsporty and un-pretencious) and have someting full-on for highdays and holidays. Like, I dunno, an Exige ? Or the GTR ? Or a higher-end Corvette ?