I'm one of the older folks on this forum. I've owned something like 30 cars so far, many bought new.
I bought a new 2006 MB C230 for my wife on her birthday (She is soooo worth it! Seriously). It was one of the worst cars I've every owned. I finally traded it in on a new BMW for less then the price of repairs i had made in the last 90 days. Understand, this car (like all our cars) was treated with respect and impeccably maintained. For example, I don't rev cold motors, I bleed brakes every year, I R&R transmission fluid every 15K miles, I R&R coolant every 2 or 3 years, etc. The average age of our current fleet is 9 years and 98k miles. I am 100% confident that any one of our cars could make a 3k mile cross country trip without anything more than gasoline and a windshield wash! Right now, with no prep whatsoever. Even when new, I didn't have that confidence in our MB.
Here is the list of problems we had with it.
1) From day one it had a drive train vibration @ 65-70mph. The MB service manager eventually admitted that MB had a problem with this. After several warranty repair attempts MB never provided a solution (in hindsight I should have used this opportunity to Lemon Law the thing).
2) The car had a tendency to overheat the right front brake rotor. I'd jack up the car in the garage with the engine off and find the RF brake dragging. Repeated warranty repairs were unsuccessful I finally "fixed" the problem by pulling the ABS fuse. Problem gone! We drove the car without ABS for 75K miles.
3) It swallowed some plastic bits that reside INSIDE the multi-stage intake manifold, which hammered one of the spark plugs closed. It needed a new intake manifold. And even though the car was driven just 3 or 4 miles after the malfunction, it killed the right side catalytic converter. The car was out of warranty at this point. This was an expensive repair.
4) The "conductor plate" inside the 7-speed auto failed, leaving the trans stuck in 7th gear. The conductor plate is a very large electrical component INSIDE the oiled part of the transmission. It sits above the valve body. This was an expensive repair.
5) Later, the valve body failed in the transmission, resulting in extremely harsh 1-2 upshifts. This required another expensive repair.
At this point I gave up on it and traded it in. It had 117k miles on it, far to soon for a well treated and maintained car to require so many expensive repairs. I consider a car with 117k miles on it "middle-aged", not "old".
The conductor plate and valve body are known weak points. At least our M272 motor didn't have the faulty balance shaft gears, which is another known problem (and a $6K repair). I thought that era C-class was a good looking car, but it was a total POS.
My son made a recent comment to me. You don't see these cars on the road anymore! When they were new you saw them everywhere. No more. They've all been recycled and have been reincarnated as trunk lids on something new.
Scott
PS Attached is a mug shot of that POS.