After defining a new segment with its low roof and coupe-like profile, other manufacturers are lining up to trace the CLS silhouette. Jaguar's new XF, the recently announced Volkswagen Passat CC, and even BMW's X6 all bank on the four-door coupe phenomenon.

Now three years on from its introduction, the CLS-class isn't going to take this onslaught parked in a dimly lit garage. Mercedes has ordered up some minor styling adjustments to keep the swoopy four-door looking good, in both CLS550 and CLS63 AMG guise.

Exterior changes are subtle, as is the case with most Mercedes mid-cycle product updates. Up front, there's a new grille featuring two large horizontal bars - down from four previously. Bigger side-view mirrors now incorporate arrow-shaped turn indicators, a theme that carries over to the new LED taillights in back. Trapezoidal exhaust tips peak out from under a new rear bumper on the non-AMG model.

The subtlety continues on the inside. A sportier three-spoke steering wheel - like the one we recently saw on the 2009 SLK-class - sits in front of an updated gauge cluster. Those AMG buyers opting for the performance package (a bit redundant, no?) will be greeted by a leather- and Alcantara-wrapped wheel as well as a speedometer that will hit 186 mph (as opposed to the standard 155) by way of a modified limiter. That extra 31 mph likely won't get much use on American roads, however.

Power from the two V-8s - 382 hp and 391 lb-ft for the 5.5-liter, and 507 hp and 465 lb-ft from the 6.2-liter AMG engine - is unchanged. And that's just fine by us.