Ok, so whilst fitting the scuttle covered in this thread:
Battery/scuttle cover.... wheres the best place to get them
I've come across a potentially serious issue with the A4. It's been covered before, but its not one I'd have known a thing about without looking for - I'd urge you all to go check this on your own car.
Basically, the drainage plugs in the scuttle get blocked up and rather than pour back out through the bottom, any rain water or whatever else that runs down your window gathers in your scuttle, effectively turning it in to a bath.
This can lead to serious issues with leaking interiors and, worse still, faults with your CCM.
Thankfully I've had no issues and it doesn't appear like I've any leaks anywhere, but when checking, mine was holding a LOT of water.
The fix I was told when visiting audi is just to remove the rubber grommet from under your battery, which I've now done.
However - I'm not convinced the grommet I've removed is the correct one, as I did so just with everything in place and reaching under the battery. Are there any other grommets around there which should stay in place?! The one I've removed is pretty large and doesn't have any holes in it?!
Its probably better to remove your battery and get a better look, but its chucking it down here just now so I just did this quickly with everything in place.
I'd recommend you all go look in your scuttle though to make sure.