An inside source at Mercedes has told Automotive news that the next generation SLK will be fitted with an optional diesel engine. It will have the same 2.2L four-cylinder turbo diesel engine found in the current C250 CDI. The power plant is rated at 204hp with 369lb-ft of torque. In the C-Class sedan returns fuel-economy of 54.3mpg and CO2 emissions of 138g/km.

The new diesel is "perfect" for the SLK, the source told Automotive News. Output is high, it runs smoothly, and it's appropriately fuel-efficient for the times, he said. At the other end of the spectrum, the AMG model is expected to pick up the hand-built 6.2L V8 engine found in the C63.