The passenger footwell on my 2001 TD4 was flooded ( probably from new ) as you can't see it because of the rubber backed carpet. I found it quite by accident one day, when I noticed a tiny drip at the door bottom front pillar, as I was sat waiting at lights. I lifted the carpet and it was sodden underneath. From new I had terrible condensation on the windscreen, most likely caused by all this water in the car. It was so bad I carried kitchen roll in the car to mop it up. Anyway on further investigation I found the leak. The water was coming in at the top of the windscreen, where the the roof rail indent, which was badly finished, meets the window seal, it was running down the inside of the window pillar, down the back of the trim at the door and under the carpet. I fixed it in two minutes after I eventually found it with some sealant. no more kitchen roll required. I couldn't believe that I had put up with all that F*****g condensation for three years, because of a stupid little thing like this. Rant Over. Give it a Try.