My old Ford Mondeo, which I laid-up several months ago and is now sitting in my driveway, has all the seats, seatbelts, steering wheel, headrests, etc absolutely covered in a white mould! It comes from the car not being used for an extended period.

There are certainly no water leaks to the interior whatsoever on that car but, over a period of time, the interior does become very damp with the non-use, which causes the mould growth. I've had the same problem with a couple of other cars which I've had sitting in my driveway unused in the past. The interiors of those cars have suffered in exactly the same way.

Since I ended up scrapping the other two cars, and the Mondeo is very likely to be going in exactly the same way, I wasn't / am not particulary bothered about the mould.

t has been exceptionally wet lately and most cars are suffering from condensation to a greater or lesser degree.

Absolutely true. The fact that a lot of people drive around with a/c off and the windows shut means that moisture is bound to build up. Doubt there's anything inherently wrong with that particular example-but I wouldn't fancy it!