I think you are both forgetting that you just own a C class. The C class is nothing like a mercedes should be. The US models are significant better regarding rattles and squeaking noises, but the standard, simple euro models are CHEAP.
The W202 C class was made as the smallest and lowest priced Benz (before the A class was introduced) and that is exactly how mercedes built the car. The euro models with manual seats, non-climate controlled heater only's, manual windows, etc. rattle and squeak a LOT. The E class is a lot better as far as the rattles and squeaks are to be concerned...
As I have posted before: you can judge by the sealant along the inner edges of the door whether the door is renewed or not. New doors come without the sealant and there is not a single chance that anyone makes the sealant as smooth as mercedes does.
David, if your car is in a good shape and you like the way it runs (with or without the second O2 sensor), what the heck whether the car has been pre-owned by 1 or 4 owners. You own the car NOW and you use it now, enjoy that vehicle and don't search for any possible failure. It is a C class and it is not new which will leaves you a lot "problems" to be found.
If you have to take apart the complete door before you can even suggest that it has been repainted, I can only say that the body shop did a good job!
The 2,5 year young C class of jjrodger will be equipped fairly well. The euro models have been upgraded by mercedes to give their customers something worth their money. As you have seen on my web page, the early euro models had NOTHING (besides power lock, power steering and ABS).
I have a lot of quality speakers in my car and have tried everything to keep my door panels from rattling to the music...but it is still a C class so I can't get rid of that either.
sekurit is still there on the windows of the C class although mercedes has sigla as a supplier of the later models as well...
We have the WURTH tar plates as well, so I think that David should be able to buy them in the US as well...
with a minor 600+k