I have a mildew metallic smell when moonroof is open. Does not matter whether AC is on or not. Noticed this the first time I had the roof open . I turned the air off . Thought that might be the issue but it comes and goes even with AC on. Not very pleasant.

After almost 20,000 miles has not gone away. Definitely not the outside and I shower every day .

 

I have the same issue on my 2014 CLA 45 and when i took it to the dealer they seem not to smell anything, as far as the C450 not yet after 6000 miles, knock on wood...

 

I have the same thing!! Since day 1. Not sure it is metallic, but definitely a mildew-y smell. Amazing that other people have this..I smell it only when driving along with the roof open..

Maybe its the smell of the grease they use for the sunroof and then the odor is blowing in the cabin?

 

https://mbworld.org/forums/c-class-w...n-windows.html

 

 

Check the drain tubes that go from the channels around the sunroof, they are supposed to drain was down through the front A pillars out below the car. Maybe they're plugged up and water is sitting in the channel or tubes mildewing? Clean out the channels and pour a little water I to the tubes and see if it drains it. You could also pour a little Clorox down the tubes, don't get it on the car finish, it'll kill any mildew. Might try a can of that canned air with a nozzle, stick the nozzle down the tubes and seal around it with a rag to try and clear the tube.

 

I had the same problem. Try leaving air conditioning in on the position with recirculation turned off for a week or so. I did this about 6 months ago. The mildew smell went away and has not returned.