I have a 1998 Mercedes-Benz SLK230 and I love it! I recently read on a web site that Mercedes is about to come out with a new line of engines for the SLK, a 2.0L Turbo, a 3.2L V6 and a Supercharged 3.2L V6. When do they come out? I'd replace my SLK for one with a more powerful engine.
The stories you've read are simply rumors at this point in time. I've spoken with Mercedes public relations, and anything they have on the drawing board right now is still classified.
However, they did say that the Supercharged 2.3-liter four-cylinder engine which currently powers the SLK will remain as a powertrain choice for several years to come. So, that would kind of eliminate the addition of a turbo charged four-cylinder to the line up.
It's a definite that the 2.3-liter will be the only available engine for the 2000 model year, but there was a hint of possible additions in 2001 or 2002.