i find sealants the best for the "blast off the dirt" usefullness.
What I tend to do with a fully detailed car (of mine) is snow foam the car, then blast it off with the pressure washer. That does about 90% of the car. I sheet the water off with the hose, they i'm done. this means i dont touch the paintwork, thus reducing the risk for any marring of the paint.
I do this every week or so and when i get chance, maybe 2-3 weeks when im busy ill give it a proper wash.
Zaino stuff is great for this.
So in summary, you can just give the car a rinse. If you have a pressure washer, you'll get the car pretty clean.
you can also buy some proper shampoo and a wash mitt. washing with this wont strip the wax. if you dry the car after, you apply another coat of colly! ;)
hope this helps! :)