Right from the purchase this was a problem car. The entire fuel system ( diesel ) had to be replaced, a warranty item. Then the front ball joints had to be replaced. This happened twice. This vehicle had fancy seat controls all of which FAILED. Brakes were bad and had to be fixed. The fuel injectors ( diesel ) failed and required THREE REPLACEMENTS. Yes, the almighty Mercedes Benz can still makes lemons. And I met people who had similar issues.
Once these cars age, they eat parts like a kid eats candy. I bought mine a year ago at 90K miles and it has been a constant headache and very unreliable. Always heard MB cars are good to 300K miles, but doubt that now. I thought I was getting a bargain, but it's not. Most parts online are reasonably priced but take days to get; local parts stores charge as much as twice what online parts dealers get, but often don't have what I need. I do much of the work myself and luckily have a reliable independent shop that works on European cars to handle what I can't; if I didn't do much of it, I couldn't afford this car. These are complex cars and you pay extra for the experience it takes to fix them. Plus they can have hard-to-solve problems. For instance, I have a voltage "leak" that drains the battery if not driven in two days, and the shop can't figure it out. Mercedes dealers are notorious for charging seriously outrageous prices for parts and service (most car dealers make more money from service than new car sales), so get ready for a shock when they hand you a bill. My car performs very well, is super comfy and the tunes are awesome ... when I can drive it. I love it when it's working right but so glad I have a second car. In short, it's a real love/hate relationship. Buyer beware.
Go for the mechanical beauty of the naturally balanced Inline 6 with the iron block. At 18:1 compression it will outlast subsequent aluminum versions. Use Power Source Diesel Kleen once in a while and keep the injectors clean and lubricated. I have had my 2006 CDI for 145,000 miles and would not part with it EVER. I have driven 1,300 miles in one sitting (several times) and felt great afterwards. MPG is best with the right tires. I had Michelins and could easily get 40 mpg. Switched to other brands and it was a little harder to get that level of MPG. The car is VERY solid and well built. Get clear impact film for the driving lights to protect them from rocks. The rear seat is a little awkward to get out of. The cloth door jambs have worn a bit on the driver's side. Great stability. I upgraded the headlight bulbs to Phillips brightest and it was a great improvement. Suggestion for MBZ, let us adjust the high and low beams individually not as one set. Honestly I would put this against any other car for comfort, performance, efficiency and longevity.
Have had my car for six months and have put 4000 miles on it, making 49,000 on a 2005 Model. It runs flawlessly and each time I turn the key is a joy. I only drive it locally in Rhode Island and have an excellent neighborhood Garage to perform required maintenance. Owner/Master Mechanic said,"You don't ever want to sell this car. It is in great condition!" And I won't...