What happened to it ultimately?
I bought the car with 110,000 miles, so I wasn't expecting a maintenance-free car. However, these last few months it has been nothing but problems.
The transmission was acting funny. My general (cheap) mechanic couldn't work it out, so I took it to an actual Benz dealer. I told them it seemed like it wasn't a mechanical problem, but something electrical. I'm sure they hear that kind of crap from uninformed customers all day, so they paid no attention to me. They didn't even take any steps to actually diagnose the issue. They just performed a transmission service which I had done 20,000 miles prior at my normal mechanic. I agreed to the dealer's service even though I assumed it would do nothing because it's possible my mechanic didn't use a synthetic ATF and maybe the Benz trans is getting upset. $500 later, they didn't manage to work out the problem.
I found this awesome dude in Tenafly, NJ that only works on Mercedes. His name is Wolfgang, so how could I go wrong? He diagnosed a bad switch in the gear selector that wasn't telling the car what forward gear I was requesting. The bad thing is that Wolfgang's service rates are almost as high as the dealer. The fix turned out to be $1,000.
Less than a month later, the car went into limp-home mode. When the car goes into this mode, it won't drive in any gear but 2nd and 3rd (I think) and generally the car won't accelerate over 40MPH. It turns out that one of the EGR valves died. When you replace one, you should replace both. That issue couped with a few other minor fixes cost another $1,000.
Now, there are still some annoying problems, but I have lost the will to carry-on in this fashion. The power steering needs attention and the climate control is really screwed up. I can probably fix both problems myself, but I'm totally not interested anymore. With 140,000 miles on the car now, there are just a ton of problems cropping up one after the other.
It's not just these recent issues that get me down, but since purchasing the car it has needed at least some sort of thing replaced every month. The lesson is that a Benz is probably not fit as a commuter car. The Benz gets an additional 12MPG on the highway than the Honda Element it replaced, but the fuel savings (and then some) are just going toward service.
What a shame.