I am looking at buying a C300 that has smoking on the headlights and tail lights. Is this difficult to remove? Buying new headlight and taillights would be prohibitively expensive.

It could be, depending how it was tinted. Search on YouTube. There are plenty of videos about that. Why don't you just ask the dealer/person you are buying it from to remove it back to stock before you will agree to buy it? I would think by having that on there would make it harder to sell the vehicle as that look doesn't appeal to everyone.

Thanks, the car is across the country so I'd be buying sight unseen. However, it appears that used headlights and taillights are plentiful on eBay for not nearly as much as I imagined.

For a 2011 model, if it doesn't have the adaptive headlight package it should be pretty straightforward. Do you know if pre face-lift w204 c300 sports all have incandescent taillights? Or LED?

I believe the LED tailights started with the facelift models in the 2012 model year. Not 100% sure on that. Maybe someone else could chime in.

May all be a moot point. Somebody has apparently arranged a test drive locally and they won't let me put a deposit on it within 4 hours of that

Plenty of used C300s out there. I'm sure you can find something closer to home you like soon enough.

This is true, but I'm trying to find the cleanest example of a 2010 or 2011 C300 Sport with a 6 speed manual, and that is proving hard to do!

I ended up putting a deposit on a local car. During the test drive at night I noticed the headlights were extremely dim. Is that because the headlights were also smoked on this other one? I thought this was the stock look for 2011s?

FYI it turns out this is most likely a factory smoke tint. It seemed dim because the headlights were aimed too far downward.