Best recommendation I can suggest to you is to layer a sealant a few coats to help removing the slung brake dust. At least this way it will be sitting on the layers of protection and not the actual paint so when you wash or polish or re-wax it should help in removal. Our most durable sealant, but can be a pain to remove is:

Klasse High Gloss Sealant Glaze

My favorite due to its look, ease of use and surface slickness is:

Menzerna Full Mollecular Jacket

Let me know if you have any other questions.

George @ Detailed Image