I would not bother. It would be much better to detail the car properly once, and have it so the majority of the dirt can be snow foamed off, jetted off at a local petrol station and then QD'd, or washed off using something like Chemical Guys Ecosmart or something when there is not much dirt on the car.
I wouldn't use a waterless wash on a dirty car, on a dusty car such as in America in California they have their place..