sisi, thats an article in Exoto catalogue (they have recently started to make also dusty models).
I made dust effect on cars since many years..and exoto ones are cool but quite heavy (to do that properly u have to study really carefully pictures of the real thing).
The ones I make are done with a base of oil paint thinnered and used in airbrush with the smallest opening u can work with (mine is 0.15).
U formerly make a real oil wash of the car body,but sometimes this trick is used to cover painting mistakes,or damaged parts.
I dont like at all showcase finished models, so glossy and clean (not at all on a race car..)
In this particular model probably the worst point is in the original die cast body of the car.
If u wanna make crashed cars u have to mantain in scale the thickness of the fiberglass body (this mean u have to heat plastics and work with it, or use alluminium from coca cola can..).
This model is 1/18..in scale u will see just flashes of body all over.
It is exactly the same effect u have to obtain when u make armored fighting vehicles damaged or burned (even more if LIGHT vehicles as trucks and jeeps)
The model anyway looks cool for real.