My car has a rattle in the trim that runs above the drivers door. It's right next to my ear and drives me nuts a few days a week while commuting to work. I usually smack it once or twice and it stops. It's been doing it for two years now. My last Mustang had a rattle under the dash that never went away.
+1 ; After a year the car is tight and rattle free, except for a small rattle coming from the plastic upper door trim. I'm going to remove today and see if I can source it out.