I found a possible solution to your problem, from Aurazine.com I found something that gets rid of crap like that. I even found some videos on YouTube supporting this products claims. Only problem I've only noticed is that the dealers are in Europe.
CarPro Iron X (AQuartz) - car paint, wheels and glass cleaner (safe for all wheels including painted aluminium and alloys). Automotive paint is porous, by using an acid salt solution on the paint surface the micro-fissures (‘pores’) are expanded by an exothermic reaction. This releases ferrous particles and caustic compounds that have developed in the paint's subsurface; the reaction agitates and loosens the particles allowing them to be rinsed away.
This is a one-step, highly effective vehicle paint decontamination, beyond what can be removed by washing or claying, with the cleaning power of an acid with a pH of 7.0, by using a neutralised acid salt
Neutralization is the reaction between an acid and a base (alkaline) producing a salt and neutralized base; common examples include acetic acid and sulphuric acid, it contains neutralised acid salt that effectively dissolve the sintered brake dust particles by forming a water soluble complex that can be rinsed away. Do not allow solution to dry on paint surface. The smell is similar to ammonium thioglycolate (its main chemical component) formulated in permanent wave lotion
It is really interesting to see the amount of iron particles residue that will be dissolved by Iron X, despite having clayed the car before hand. This product definitely offers advancement in paintwork decontamination
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2008 SR5 4x4 V6 Salsa Red Pearl w/Taupe Interior
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