The next-generation SLK test mule has been spotted making rounds on a track, prepping for a possible 2010 release date. The 2011 Mercedes-Benz SLK will spot a similar, if not same, hard top folding roof, get some new LED fog lights as well as be similar in design to the new SLC Gullwing in the front. Our friends over at GlobalMotors.net have also noticed that the side mirrors are attached to the doors on this prototype, but that could be only temporary. In terms of engine options, a diesel 2.2 liter 4 cylider twin-turbo may also be available upon launch, and some say that even a hybrid version will available. The rumor of an SLK Gullwing has been dismissed by our Insider, so don’t hold your breath for that one.