can water leak into the driver side floor board through the vents on the firewall? everytime i wash the car or it rains it will leak and collect about 1/2 an inch of water on my floormat.

at first i thought it was the sunroof, but i put a tarp over it rained today and leaked inside still. is there a clear passage from the windshield wipers to the floorboard for water to travel through?

this is getting annoying...

 

Have someone run a stream from a hose in the area you suspect is leaking. While that's happening, crawl under the dash with a flashlight and look for dripping water. Could be several things including the windshield seal, rust holes, and so on.