Section IV: Dusting/Between Washes
Simply put; the easiest way to keep your car clean is to keep it garaged.
I don't have this option =/ my car sits outside, day and night, often in the blazing SoCal sun with construction area dust and car exhaust crap flying all over the place. I used to use an instant detailing spray/microfiber but recently I've found a quicker, handier way to keep my car clean:
The California Car Duster!
If you live in a dusty area (or are stupid enough to make a car wash DIY when ash is falling from the sky), then you need one of these. Use it only when your car is cool and in the shade. Just hold the duster barely over the surface of your car and move it in big sweeping motions. It'll suck the dust off your car (static something).
Afterwards, just shake it out. Ta da! Clean car again.