It depends on the nature of the "dirty" my car is. If I've avoided rain all week, then the car is just dusty. In those cases, there's no harm to be had and alot of efficiency to gain in using Meguiar's Quick Detail spray with a clean terry-towel, or simply a wet-rag/dry-towel sponge bath. But if the car has been driven in the rain, and is caked in road-grime, it has to be washed. Zymol makes the best car wash solution, for maintaining your wax job and being therapeutic to rubber trim. Anyhow, in Florida, it's a rare week that you don't get caught by at least one rainstorm. Especially in the Spring and Summer. Be it silver, or black, or whatever I'm driving for daily use, I've got the suds and the hose out at least once a week. It's great exercise.