Spy photographers in Germany have snapped what appears to be the first ever photo of a Porsche Panamera prototype. The Panamera is a four-doour "coupe" designed to rival the Mercedes CLS and Aston Martin Rapide. So far, Porsche has only released an official sketch of the car. Since may design cues from the sketch — such as door cuts — are not carried over from the sketch, we suspect the vehicle pictured may be a test mule rather than an actual prototype. In late 2005, a Porsche spokesperson said the automaker would unveil a concept version of the car in spring 2007. At that time, we should get a good idea of how the finished car will look.

Porsche's Wendelin Wiedeking announced in an interview just days ago that the automaker's new Panamera four-door "coupe" began its testing marathon at the challenging Nürburgring over the last week. Now, spy photographer Brenda Priddy has snapped some photos of one of the first prototypes, still wearing heavy disguise. The entry-level powerplant will be Volkswagen’s 3.5-liter six-cylinder engine with 300 bhp, while Porsche’s own drivetrain will be a direct-injection eight-cylinder petrol engine, available in naturally-aspirated guise (350 bhp) and with twin-turbo (560 bhp). When it hits the road in 2009, Porsche hopes to be able to sell 20 000 units annually. In late 2005, a Porsche spokesperson said the automaker would unveil a concept version of the car in spring 2007. So far, Porsche has only released an official sketch of the car. Gallery after the jump…

Editor's Note: Text previously published 10/05/2006

A prototype for Porsche’s upcoming all new four-door coupe “Panamera” is currently being tested for the first time at Nürburgring as well as in the south of Spain.

The new model will be released in spring 2009 at the Geneva Motor Show allowing Porsche enough time for a meticulous development of its fourth model range before market introduction.

Panamera is set to meet the competition of four-door coupes like the Mercedes CLS, which is on the market and of which 24,000 cars have been sold already. Simultaneously, Volkswagen is developing a four-door Passat Coupe, and Aston Martin premièred a four-door coupe concept named Rapide at the last Detroit Motor Show, which caught a lot of attention and is likely to go into production.

Porsche’s Panamera is going to be assembled in Leipzig, Germany thus creating 600 new jobs. The body will come from the Volkswagen plant in Hannover and the engines will come from Porsche’s home base in Stuttgart. Plans are to produce 20,000 units per year from 2009 on.

Initially the front-engined “family” Porsche will come on the market with an 8 cylinder 350hp engine and/or with a biturbo engine delivering 560hp. A lesser costly version will be powered by a 3.5 litre 300 HP fuel engine which is already being used in the Cayenne, four-wheel-drive is standard equipment. The top-of-the line Panamera gets the 10 cylinder 700hp engine coming from the Porsche GT. Seen in the attached photos this engine is currently being tested by Porsche under the body of a BMW 5-Series station wagon.

Furthermore Porsche and Volkswagen are developing a Hybrid version of the Panamera using a 6 cylinder fuel engine combined with a 60 kW electric engine.

Initially the front-engined “family” Porsche will come on the market with an 8 cylinder 350hp engine and/or with a biturbo engine delivering 560hp. A lesser costly version will be powered by a 3.5 litre 300 HP fuel engine which is already being used in the Cayenne, four-wheel-drive is standard equipment. The top-of-the line Panamera gets the 10 cylinder 700hp engine coming from the Porsche GT. Seen in the attached photos this engine is currently being tested by Porsche under the body of a BMW 5-Series station wagon.