So yesterday afternoon, a buzz which sounded like it emanated from the right side front door occurred. Now my C has been really tight and without any rattles, or buzzes since new. So this buzz for the past 24 hours was driving me crazy. I tried pressing against different parts of the hard plastics on the right side door and B pillar. This did nothing. Now sound travels and bounces off objects, so now I am thinking the sound is coming from the A pillar. While I am searching this new area, I pull down the sun visor to see that the mirror door is open. I slide the door closed and the buzz is gone! So the next time you hear a buzz from the front, check to make sure your visor mirrors doors are closed!! Now my car is rattle and buzz free again.