While driving this afternoon i heard some rattle noise in the rear end of the car, as if a stone or coin was rolling around. when i got home i opened the carpet lining in the rear of the car and indeed found a little stone rolling around. that took care of the noise, but then i began wondering how it got there since i have never loaded the trunk of the car. i began looking around and found some kind of vent by the manual gas door opener on the rear inside left panel of the car. the vent is just lightly closed by some plastic that flaps around. there must be some purpose for that vent that most than likely let the stones in the trunk. does any body know what the use of that is? it is not a very important issue, i'm just curious.