We already have a fairly good idea as to what the new 2012 BMW 6-Series will look like following the reveal of the Concept 6-Series Coupe back at the 2010 Paris Auto Show, as well as a leaked shot of the new 6-Series Convertible, which was taken while the car was in a photo shoot.

However, there are some details that we can gather from this latest crop of spy shots, showing the new 2012 BMW 6-Series Convertible with its top down. Prototypes of the 6-Series are testing in Europe and have been captured by spy photographers on several occasions near BMW’s headquarters in Munich or around the Nurburgring circuit.

Comparing previous spy shots of the Coupe with these latest shots of the Convertible, several clear differences can be seen. The rear side windows are a different shape on the two cars, the roof profile is also slightly different and the rear window on the Coupe is slightly wider than the one on the Convertible as well.

This suggests that BMW is preparing two separate 6-Series models unlike what it did for the latest Z4 Roadster, which now only comes with a folding hard-top roof. BMW will sell both a 6-Series Coupe and a 6-Series Convertible with a conventional soft-top roof.

The current 6-Series has proven to be a sales success, with numbers averaging just on 20,000 units per year. BMW doesn't want to risk hurting sales of the next-generation model so for the new car designers will be dialing down the controversial styling. The spy shots reveal a much sleeker look and a wider, more purposeful stance.

Inside, the new 6-Series will feature plenty of luxury appointments as well as an eight-speed automatic gearbox with paddle-shifters. The current engine lineup is expected to carry over relatively unchanged, but there’s chance that the range-topping M6 model may not be replaced as BMW is planning a new standalone high-end sports car to fill that segment.

Expect the Coupe to launch in the middle of next year, with the Convertible model to bow in before the end of 2011.