Perhaps being labeled a “Climate Pig” by Greenpeace has motivated Porsche to develop a hybrid or, more likely, the marketing folks at the German automaker see a new market segment and some bucks to be made with a little greenwashing. It is estimated the Cayenne hybrid will get about 24mpg (current model gets approx. 19mpg highway).
In any case the 2009 Cayenne Hybrid will feature a full-hybrid design.

This from the press release:
“where the hybrid module (clutch and electric motor) is positioned between the combustion engine and the transmission rather than having the hybrid drivetrain branching output along various lines and in various directions via a planetary gearset. Porsche selected this design because the in-line configuration of the hybrid components are more compatible with the existing Cayenne platform, this system in testing is more fuel efficient, and because this configuration is a better fit for Porsche as it will provide improved acceleration and engine flexibility compared to a conventional Cayenne.

Coordinating the car’s three main components – the combustion engine, the electric motor and the battery – is the Hybrid Manager, the heart of the Cayenne Hybrid. The Hybrid Manager, which oversees some 20,000 data parameters as compared to only 6,000 data parameters for a conventional engine, is one of the most powerful technologies found in any hybrid vehicle.

Other unique features of the Cayenne Hybrid designed to decrease fuel consumption include the power steering and vacuum pump for the brakes, as well as the air conditioning, which operate on electric power. Technical components, such as the oil pump in the Cayenne’s automatic transmission, have been replaced by electrically powered units. The Cayenne Hybrid’s electro-hydraulic steering – a first for a vehicle of its kind, will ensure the Cayenne Hybrid drives like a Porsche with predictable and safe handling characteristics and the agility that is expected of a Porsche SUV.”

full businesswire release
(note: pictured above is the totally redesigned 2010 Cayenne)