I am having an issue where it rains and a lot of water ends up collecting in the rear passenger floorboard. I tried taking it to a mechanic a while back and he couldn't identify the leak. He said he checked all the outside seals with soapy water and may have also checked the sunroof drain. After searching around in general I have found some people with water leaks but none of them in the same spot as mine. I also noticed than when I parked that some water is slowly dripping underneath the car to the ground directly below where the leak is though I don't imagine the source of the leak is underneath the car as the water leaks in from the rain when it is parked.