I now have 18,000 kilometers on my 2005 SLK350 and it is turning out to be everything it promised and remains problem-free despite the usual spirited driving. It's fully loaded. The only thing I had to do was lubricate the hardtop rubber at the points where it folds. Did this once, was very easy to do, and it got rid of the little squeaks that had developed in the dry weather. Have driven it all winter in Northern Ontario, Canada on a set of proper winter tires, and the automatic climate-control system is fully up to the demands of even the coldest weather up here. The SLK350 is a perfect all-season sports car, and has a great engine. I have never had to top up the oil.
Acceleration, handling, safety, hardtop-down flexibilty, and fuel economy considering the ample power.