As I have mentioned in my other post (Starting Problems) I had reason to remove the side covers in the boot to check the brake light bulbs. I have just had the car in the local dealership a few weeks ago for various work including the fitting of two new batteries. They said one had sulphated and the other was replaced under warranty as it was not holding its charge.
I noticed that around the base of each new battery there was the remains of battery acid crusting. They had simply removed the old batteries and inserted the new ones without even cleaning up the battery area. I removed the batteries and this is what I found. After removing the white crusting, much paint also flaked off. I cleaned the whole area and put Kurust on the bare rust, then waxoyled it. If this had been left it would have gradually corroded the boot floor away! At their rates, you don't think you have to check all their work!
Thanks Robert Stern BMW of Worcester (NOT!)