The circled area in the picture below is precisely where my buzz or rattle is. And it's in the EXACT same spot on the left and the right doors, so that shows a high level of manufacturing consistency, so the buzz is most likely found on other 02-06 Mini Cooper models as well. However, after an hour+ of research here, I find little or nothing on these terrible rattle / buzzing sound. Does know anything about this vibration or how to eliminate it?

notes:
-pressing on the area circled in the photo stops the buzzing / rattle sound.
-seems to be temperature dependent, so expansion/contraction of door components changes the level of buzzing.

 

its most likely the little tab dealys that hold the panel to the door frame. its really easy to take the door off.



here are the tabs. ive found they do in fact rattle. i put some GTmat on them to stop them from moving around (you can try glue, or anything that will wedge them in place)

 

Bet it is not a defect....
But rather the door card/panel has been removed, and reinstalled either wrong or with a bad Clip....
Yank it off...and fix it...to call ANYTHING A FACTORY DEFECT in a 10 year old car is actually kinda funny....lol...and if it had been an issue...it would have been fixed when new at the dealer when it was pointed out...about 8+ years ago....lol.
Sounds like some tape to tighten it up...maybe a new clip...and you will be good to go...but to "reach" and call a buzz or rattle on a car 2 full generations out of production a factory issue is beyond reaching....heck...do a search....15 years of gen1 cars ...and you might be the first...the first in recent memory at the very least!!

 

My 2002 has this issue as well. Thanks for the tips.

 

What till he starts to hear the rattle in the rear bumper area. Grr!!!