OK, here it goes.
After buying a Clio 1.8RSi I have been plagued with a leaky sunroof roof.
There are 3 things to check:-
1) The aerial - Best thing to do is take it off completely and bed it on black silicone.
2) Where the plastic frame meets the metal roof of the car. After time the plastic frame starts to warp letting water in from the outside edge. Best thing to do here is run some black silicone round the outside edge or you could use silicon grease.
3) The rubber seal which makes contact with the glass. Try running a thin piece of card between the rubber seal and the sunroof from the inside. If you can push it all the way through easily then the seal will not be making good enough contact with the glass. On a 1.8RSi Renault wanted £82, yes £82 for this rubber seal. So what I ended up doing was running a thick bed of black silicone on top of the existing rubber seal and to top it off a layer of silicone grease once it is dry of course.
For a new sunroof frame inc the rubber seal Renault want £215 which is why it lead me to try my own methods.
Hope this helps
Rob