Duster, then follow that up with a spray detailer like McGuierrs or similar. I do this all of the time, especially this time of year. I park in a shell parking lot at work, too, so yesterday when I got home, I washed my fenderwells and tires only just to get the wet shell mud off of the car because it was raining yesterday when I got to work. I love my daily driver but I am not fond of punishing it daily with the dirt/grime. I just waxed it Sunday, too!