Well if you just want to talk W211 problems, the things I've done over the past 7+ years not including engine stuff are the motor/transmission mounts, steering angle sensor, front springs/struts, just did rear shocks, going to do the rear springs soon, new pads/rotors all around, new parking brake shoes/spring kit, sway bar links, tie rods, upper/lower control arms. Had some bad luck with CV joints, but MB sells just the joint for $40 so I actually had the left and right cv joints rebuilt instead of getting an aftermarket cv joint, did that to the left one first and it was junk, caused a vibration. Right now I have a bad keyless go door handle, the passenger side, probably won't replace it as the other 3 are still good, they're over $200 each, the W212 has a better design, on the W211, it's a rubber membrane that covers a switch and it corrodes, but on the W212, it's just a sensor where water doesn't get into it. Seat belt retractor stopped working once, took it apart and blew it out with air and it started working again. Biggest pain is probably the 18 inch tires, lots of flat tires and bent/cracked rims, think it's over 3 cracked rims and 2+ bent ones. Oh and the wires in the trunk are badly routed so a ground wire goes so the license plate light, power trunk closer might go out, but it's an easy fix to patch the wire. Mine is loaded though, bixenons, parktronic, pano roof, power trunk closer, folding rear seats, bluetooth, ipod cable, real leather, keyless go, etc.