I had a rattle from the passenger side. It sounded like it was coming from the area behind the seat. Also it was more of a buzz sound, like two pieces of sheet metal vibrating against each other. Well I went to the dealership for my first (free) oil change and asked them to go for a ride with me...no noise. Ok, well while I'm there we find the bad window motor and order the part. Today as I'm driving to drop the car off, there is the noise. The tech drives with me to my office (to drop me off)...no noise. Hummm, maybe it because there is weight in the seat. When he drives back, alone, he hears the noise!! Found that some metal "ring or tab" under the passenger seat was making the noise and taped it. Problem (so far) solved.