Recently noticed the rear seat belt wet after car washing , the common audi problem with cloged sunroof drain . The problem was to find the drain out . I know that for B5 there is procedure to take out the rear bumper , for B6 much easier , the rear wheels liner has to be removed , even would be enough to unscrew only the front T25 torx screws to fold liner aside . The clean out at the top of the wheel arch .