These latest rounds of spy shots are probably the best images yet of the upcoming Porsche Panamera, and they leave us wondering if designers will be sticking with the bland lines seen on this test mule. It’s still early days, as the Panamera isn’t expected to be officially unveiled until the 2009 Geneva Motor Show, but it’ll need to pull off something spectacular to compete with rivals like the Aston Martin Rapide four-door.

What we do know is that the Panamera will be no slouch, with powerful engines from the heavyweight Cayenne SUV carrying over into the new sedan. Top of the list is the Cayenne Turbo’s force-fed V8 engine, expected to deliver in the vicinity of 560hp, followed by a smaller and more economical V6 model as well as a new hybrid version whose drivetrain is being developed with Volkswagen. Click ahead to see the full images over at Autoblog.