I'm not going to give any spoilers. Here's the link to the result of R&T's CTS-V vs. E60 M5 track showdown:
CTS-V vs. M5
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2013 Audi S6, Ibis White
2008 E90 M3, Jerez Black, Black Nappa, Brushed Aluminium, 6-speed, Premium, Tech, Cold Weather *sold*