I thought I would share my findings so far on this one. I have spent a lot of time today stripping out the trim in the cabriolet roof storage box, and taking out the rear seats and rear side panels. This is what I have found so far, most of it by touch and not sight as even with the side panels off and some sound deadening removed, there is just so much (control boxes, looms etc) in the way that you can't see these drain hoses. There are in fact two drain hoses coming from under the seal of the roof storage compartment, which are located near the joint with the rear side window seals. These fall away over the rear wheel arch towards the front of the car and part way down join together into one hose via a Y-piece. The single hose then continues down the leading edge of the rear wheel arch and then appears to be attached to a spigot on the floor pan, about 6 inches in front of the rear arch and 6 inches in from the sill. The hoses are running clear, however the water appears to then drain onto plastic liners on the underside of the floor pan. How strange! Any way I seem to have found the problem. There is a plastic spigot pop-rivoted to the underside of the drain channel, under the seal of the roof storage compartment, to which one of the drain hoses is attached. The seal between the spigot and the body looks like some cheap type of foam that is just perishing, so that when water runs through the spigot, instead of going down the drain hose it runs down the inside of the body as described in my previous post. I have got to try and drill the pop rivets out and make a new seal (not easy with all the folding roof mechanism). It just seems a very cheap way that Audi have made this seal. As mine is probabaly one of the earlier cabriolets, this may be a problem more amd more of you will see. Hope this is useful should you ever need it.
malc
