[Nick M3]

For embedded brake dust, Sonax is good.

For really nasty stuff, muriatic acid is really, really effective. It saved my Superleggeras from the embedded PFC97 brake dust when I was ready to refinish them.

Before claying, I highly recommend spraying the car with Iron-X. It's basically Sonax for the car's paint but works better on the regular paint for whatever reason. (It's also safe to spray the paint with Sonax, but the Iron-X works better.