The new four-door--presaged by the German carmaker's 2008 Concept Fascination two-door shooting brake revealed at that year's Paris motor show--is among a throng of niche-market models under consideration by Mercedes boss Dieter Zetsche.

"We're seeking to improve our returns by better utilization of existing platforms," a high-ranking Mercedes source told AutoWeek. "A derivative of the next CLS is just the tip of the iceberg."

Like the new CLS sedan set to go on sale in North America in early 2010, the CLS wagon will be based on a lightly modified version of the E-class. The two will share the same styling up to the trailing edge of the front doors, but a heavily sloping roofline and angled tailgate similar to that seen on the Concept Fascination will give the CLS wagon greater versatility and a much larger trunk than the CLS sedan.

Code-named the X218, the CLS wagon will premiere at the Paris motor show this September. Production begins in early 2012.

Stuttgart insiders say plans for a CLS wagon have existed since the first-generation CLS was launched in 2004. "We built a one-off model that was originally slated to be shown in concept-car form at the 2003 Frankfurt motor show, but it was pulled at the last minute and replaced by a lightly veiled version of the production CLS," a source said.

Plans call for the CLS wagon to receive a range of V6 and V8 powerplants that will be revealed in June with the debut of the CL-replacement S-class coupe. The engines promise a 25 percent reduction in fuel consumption over the current Mercedes V6 and V8 powerplants, thanks to the adoption of both turbocharging and direct injection.

CLS wagon models will be rear-drivers, but Mercedes also is likely to offer all-wheel drive based on the E-class 4Matic.