I too am in the same predicament, Black car, cleaned it a few days ago, and its covered in dust. Only solution I can think of is one of those dust brushes you find.

I just would hate to scratch the paint using one of those, but am unsure if they will scratch it.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon - Sold
2006 E350 Wagon - 368 - Dead
2015 GL350 Bluetec - 197U