I purchased an 2003 SLK 230 with 150,000 miles as a side project. It did not run or even have a key when I purchased it. Only a title. I had it towed home and have been working the last couple of months in my spare time getting it going.. That said after faxing my title to MB dealer and getting a key was able to get AAA to jump it to life. It then died again to find that some the connectors were corroded. After a cleaning it, it started every time.. I was told the Cat Converter was clogged and sure enough it was. I cut it off for now and will have muffler service weld another in its place soon. But that said found a average compression of 125, 130, 130, 130 in cyl 4 -1 respectively.. While the Computer code indicated a misfire on Cly one and that #1 had one of the coils with the black insulation melted off. I decided to buy new coils and plugs. And now it seems to be running normally.. Oddly enough . no check engine lights yet.. With no Catalyst? I still have a check list of things to do.. But having a great time so far... Only one discouraging post kind of made me upset about the SLK. Thanks for your posts!