I think that perspective is that of Caddy, and while they may be experiencing a come back, they won't threaten the likes of Mercedes and BMW, or even Audi. Numbers alone aren't what compel someone in a purchase decision.
That said, if you're going to draw comparisons, it's fair that you look at the facts on each side.
Nurburgring Ring Times:
2012 M5 (Pre-Release): 7:54
2009 CTS-V: 7:59
2005 M5: 8:13
Have you driven around the ring?
Do you track luxury cars as a hobby?
If not then I don't see why this is anything more than chest beating. The majority of shoppers wouldn't even know what the term ring times meant if asked. Cadillac like Lexus has learned that shoppers consider anything European to be of greater luxury and prestige than a similar product from America, Japan, or Korea. In order to complete at this level Cadillac must build cars size matched to German offers (The CTS was more of a tweeener - 5er sized at 3er pricing). The ATS looks fairly dull but it will have nicer wheel offerings and the eventual V trim which will no doubt look much for down for mean business.
If anything the fact people flaunt ring times these days is a sign of how much the rest of the world has caught up to BMW or MB. Audi meanwhile isn't on the same level either, Tier 1 or the top mass luxury brands are BMW, MB, and Lexus.