It might be coming in through the doors, running down the window due to an old seal. Or the door membrane is damaged and water getting through there. This is a common problem on some BMWs.
Hi, not my car as I'm still looking around for one but in the last few days quite a few YouTube videos have popped up on how to repair this problem. It seems that over time the glue deteriorates and the fabric shrinks causing the window and roof to part company. Is this a common problem with A5s? It hasn't happened yet on my 21 year old BMW E85.
Brill, £140.00 seems okay to me, the diagnostic company that has fixed my wife's Ford Focus for a couple of things is £150.00 a time. Vauxhall charged £75.00 for a diagnostic for an airbag light on our Zafira and couldn't find the problem. Grrrrr.
I don't think the tyre depth is that bad considering it's a used car and it wouldn't bother me, just allow for the cost of replacing them. More important for me would be the age of the tyres and if they are a good make and all the same. I always think that if the tyres are all matching and a good make that the owner hasn't scrimped on the servicing.
We have used a company in our area that deals with this sort of problem. I know that the local MB dealer sends their cars to them if they can't sort the fault. Perhaps there is someone like this where you are. The only off putting thing is that they charge an initial diagnostics fee of £150.00 every time. But they have been able to sort us and family members. Mike.