My rear left window rattles when the bass from the speaker pumping, i went to fiat dealer, they said warranty doesn't cover rattles and squeaks if the vehicle is more than 3 months old... i'm not sure what is the problem, but i think the window is not tight, sounds like it hitting the door panel... any ideas guys??will dynamat fix this??

Are you sure it's the rear window? I had a similar problem - really loud rattling when the bass lines kicked in. Turned out to be the seat lock catch on the rear left passenger seat bench, I tied some insulation tape around the arm the lock bolts on to and it solved my problem.

Problem is once you fix one rattle you can easily hear others you couldn't before!

G'luck.

check the parcel shelf it clipped in right and sitting on the rubber bits

Yeah, i'm sure its the window, coz everytime i hold the window, its not rattling... u recon if i put dynamat will fix this??