Being that you have an 00+ you may possibly have a door thats leaking into the car... The door drain system is actually set up behind the door panel... There will be a bead seal of sorts that will have to be cleaned, as well as the doors surface and resealed to kill off the leaks... That unless you have a sunroof... If you have the sunroof there is a chance that it could the a sunroof drain...
Good Luck
