I have just purchased a secondhand audi 3.2 roadster, to my horror the floor on the passenger side was soaking within days of using the car. The garage was really good and took the car back but seemed unsure as to whether they had 'fixed' the problem. One heavy rain shower later the passenger footwell was soaked again. I went on-line discovered this forum and followed numerous threads of people having the same problems.
I took the car to audi main dealer and they quoted me over £600 min to fix it. So I was determined to take matters in my own hands first and save all the hassle of fighting and/or paying more money to get it 'fixed'
I checked all the drains and potential points of entry to the front of the vehichle, noticing that someone had glued the rubber join in the door seals on the passenger side (so this had been an ongoing issue with the previous owner) I then checked around the back of the hood externally to check for perforations in the hood below the bodywork (it's like a 'u' shaped channel. this appeared fine. So I then realised this 'U' channel collects water and deposits it into a black plastic tray, which is situated just under the roof hinge behind the metal roll over bars. It's easy to feel for them or get a small high powered torch and you will see them. Leave the hood up while doing this.
Once you have located the black plastic collection trays (one on each side) you will notice a cable clipped inside it, ignore this. In the middle of the tray there is a drain hole with 'x' covering it to stop any debris entering it. I then poured water from a kettle into the side of the hood externally that was dry (I pushed my fingers between the hood and external rubber seal to allow a lot of water in) I then watched with my torch and saw all the water escape. I then repeated this proceedure on the problem side and saw it well up and overflow into the car. I then got some BT cable and threaded it down the 'x' covered drain then suddenly it drained and I noticed water and lots of decayed material to the front of the back arch on the floor. Success the car is now bone dry.
I also realised that when the hood is raised and lowered there is potential for small leaves to find a way in to the 'u' channel I found a few in there and I reckon that it was this that caused it.
These cars are so well engineered only adverse or unusual events will cause problems. It is always something simple that will cause it. Routine checking of all drain holes say every year will sort this problem for 30mins of your time. Or alternatively you can pay the dealership numerous visits and well in excess of £600.
I can't believe such a small thing is causing such a big problem for owners. I'm happy to correspond with anyone else who has this problem.