I have a BMW 328 with less than 100,000 miles on it. I live in western Washington so you get the picture reguarding 10 months duration of doom and monsoons. Anyway, the windows are rarely opened either due to rain or because is blazing hot and the air conditioner is on. Receintly the drivers door and later the right rear (no one ever rides in back) electric windows died. They were quickly replaced and the inner panel sheet plastic was resealed. Now I keep finding pools of water in the right front/back and occationally on the left front floor. The lads that replaced the door motors are above reproach and guarentee there work. The car has been back 4 times to pull the door panel, look for a source of the water, reseal the doors. Also to check the drains in the sunroof which are apparently open. Only once did I note that the water in the right front seemed to be leaking from under the horizontal plastic kick plate next to the seat (at the front edge where is joins the carpet). The good lads have thrown up their hands and suggested that the front windshield seal may be at fault (this is the factory windshield). My concern is if it is taken to a auto glass shop there is a fair chance that the windshield may break in the removal and resealing, thus I’m out the money for a new windshield and it still may not fix the problem…what a pane. I’m druid so I must say “for the love of friggin “SPRING TIME”, must I sacrafice a virgin (hard to find in the NW) to stop the incessant leakage?” BMW’s resale is poor when you have mushrooms growing in the carpet…De Oppreso Libre.
I’d be very reluctant to replace the windshield unless you know the leak is from there.
It might be possible to find the leak by spraying the car heavily with water with a UV sensitive dye (perhaps a hose end that’s made to add soap would work) and watch with a blacklight. I’ve never tried this, but it’s an idea to consider.