Traditionally the term coupe (or coupé for the mineral water crowd) referred to a two-door car exclusively, but that hasn't stopped nearly every auto maker in Germany from pinning the label on a four-door with some sort of curved roof. The tradeoff seems pretty much the same in every case—a graceful arc improves aesthetics while simultaneously rendering the rear seats off limits for tall people. We generally like the idea in principle but the results are mixed. Audi was way ahead of the curve (get it?) on this, with the gently sloping top line of the A6 appearing over 10 years ago. But they seem to be moving away from it now, or maybe the rest of the segment has just gone further with it. Mercedes-Benz is really close to having it right with the CLS, but something about that bulging rear fender flare doesn't sit right. It's a liposuction away from being a truly elegant design. BMW attempted to apply the roof style to an SUV with the X6, and in typical BMW SUV fashion, the end result is a visual abomination. Volkswagen renders it best and most simply with the CC, and coincidentally it's by far the cheapest option. Nice when it works out that way, isn't it?