[jwzimm]

That is corrosion in the aluminum underneath the paint. If you chipped off the paint you would find white powder (aluminum oxide). Not sure about the BMW corrosion warranty but you would think, being only 3 years old, they would want to replace it.

I am having my shadowline trim on the door sills (top of the door on an e92) replaced today due to what looks like surface corrosion. The rest of my trim is pristine but these pieces are turning white.