My Grand Am GT is leaking on the passenger side only, and if it's really wet, the rear seat floor on the drivers side gets a little damp. I don't know where the leak is coming from, but my best guess is either a vapor barrier issue on one of the doors, or a body drain (weeper tube?) clog in the front of the car. The car only gets wet when it rains, so it is not the heater core/AC, and to further prove that, it is confirmed to be water that accumulates on the floor, not heater core fluid. Thanks!