Who ya gonna call, Dust Busters? I have never wanted a black vehicle for the very reason you mentioned. Very hard to keep clean.
Seriously, we notice the dust as well. But, we are near a dirt road and the passing vehicles kick up quite a bit of dust. What are the roads like in your area?
I was speaking to a friend of in the US and he suggested it was coming on the jet stream from the Sahara in Africa. So I guess we have to hope that global climate change will cause rain to fall on the dry areas of Africa so we don't continue to get their dust. See the link below for the story on African dust causing Algae blooms in the Gulf of Mexico.
Top Story--Images of Saharan Dust Moving Across Atlantic, June and July,1999 - August 28, 2001