The current generation of the SLK roadster has served Mercedes-Benz well over its life since introduction in 2004, and like all cars its once-cutting-edge design has become somewhat tired despite a mid-cycle facelift. An all-new SLK is in the works, however, spotted on numerous occasions testing in Germany and previewed in our renderings. These latest spy photos show the car in much less shape-hiding cladding than previous shots, revealing a sleek but not pointy front end and a trim and rounded rear.

The new roadster is tipped for introduction in early 2011, after going on a strict diet and gaining some cargo space--and possibly gaining a sporty new engine. The next-gen SLK will drop around 200 pounds in weight while adding a bit of space to the smallish trunk, increasing capacity to 11.2 cubic feet. That will definitely make the vehicle more useful, both for trips to the golf course and weekend getaways. Despite the gains in storage, onlookers claim the prototype seen here sits lower and is slightly shorter than the current model.

A new engine may also be in the mix, with a 300-350 horsepower 3.0-liter twin-turbo V-6 tipped for release some time after the car's official debut. The launch engines will stick with the current tried-and-true lineup of gasoline engines, with evolutionary developments expected. There's also talk of a possible 5.5-liter twin-turbo V-8 generating over 470 horsepower for the AMG version.

Additionally, there's also the possibility that overseas versions will get the 2.2-liter four-cylinder diesel found in the current C250 CDI. Rated at 204 horsepower and 369 pound-feet of torque in its C-Class application, the engine would be sporty, but whether Americans would find it palatable is an open question. Mercedes-Benz has discussed bringing diesels to the U.S., but in the GLK and C-Class, not a sporty model like the SLK.

The car's LED daytime running lights, common to all of the automaker's most recent models, are obvious. The door-mounted side mirrors stand out further on thinner stalks than the outgoing model, while the general proportions of the car with the top up seem to reflect a longer hood and more rearward seating position.

The sharper angle between the rear of the hard top and the rear deck area also mimic the SLS AMG supercar to a degree, though the real design cues shared with that car are expected to be located around the front fascia. At any rate, it's clear that Mercedes-Benz has dumped the controversial front end of the current models for something new.