Looking at purchasing my first Mercedes, a 2005 SL500 with 47K miles. Exceptionally clean. I'm an automotive electrical engineer by background, and an hobbyist wrench, so I can handle most DIY fixes. But since I've never owned a Merc before, and am simply responding to lust over the SL, I have signed into this forum to ask advice. I've read I bit of discussion here regarding suspension issues, and wonder if there's an expedient way to verify that the system is OK (car looks to sit level) or if there are other common problems I should check into before purchase. Any/all advise vastly appreciated!

 

Other than using normal indicators to tell you the car has been taken care of, is the ABC fluid level right and is it clean, etc... Obvious stuff like does the body sink after being parked is an indicator of some of the valve blocks not maintaining the pressure isolation. I am not sure there is a way to tell/predict what it will do in the future. I have heard of people doing the old fashioned bounce test, but I would have thought that being hydraulic would make that test a moot point. I know my accumulator was groaning as it went bad, and I understand the pump makes the same type groan when it starts to fail. But that would be obvious to you. Maybe a pressure test will tell you if the pump is on its way out.
The suspension ABC system is probably the costliest maint on the horizon. (assuming all the other maint has been kept up). Its hydraulic and 70-80K miles is when I usually hear people start talking about the failure. Just tell yourself the repair can be up to $5K at the dealer if they have to do it all. Almost half of that is the tandem power steering / hydraulic pump for the system. You can do the preventative maint on the system and stack the deck in your favor, but it is like a ghost in the closet, you really can never rule it out. Of course if you do all the work yourself, you can save a bundle.
Other than that, I haven't seen a lot of problems. I drove a 98 SL500 for about ten years, and bought a 07 Sl550 about a year and a half ago. As far as Mercedes in general: my experience is that if you spend a few bucks and keep the maint up, you will have less failures than other brands. The cost of some repairs is higher, but I cant think of any I ever had to have done twice. Spend the money, get things done right, and drive the hell out of it. That's the way I do it. Seems to be working.
The only other advice I would give you is regarding tires and wheels. If the car has some pimp mobile rims, get rid of them and get the stock size and put the recommended Michelins on it.
In my opinion: When everything is in order on those cars, they are an engineering marvel, and it is apparent from the drivers seat.
Another note: from what I read on here, it sounds like buying an SDS is worth its weight in gold.