(Image credit: AutoWeek/AutoSpySpain for Brenda Priddy & Co.)

It seems as if we've been hearing about a four-door Porsche sedan for 20 years. (Oh wait, we have.) Now AutoWeek is reporting that Porsche's Panamera sedan is finally headed for a debut at the 2009 Geneva motor show next spring—meanwhile, engineers were apparently busy putting a couple of prototypes through their paces on the roads of Europe.

The report said that the car's powerplant lineup is expected to include a base 3.5-liter six-cylinder engine from Volkswagen that makes about 300 hp. "Porsche is also developing a direct-injection eight-cylinder gas engine to crank out 350 hp in normally aspirated guise, and a whopping 560 hp after twin turbos are mounted." Meanwhile, a V6 gasoline-electric hybrid, based on the powertrain Porsche will introduce in the 2010 Cayenne, also will make its way into the Panamera, the article said.