Well, they say you should change the filter when it's brown, but I can't tell that too well and basically change it whenever I kill of a bottle of the soap. I use the fine filtered mist from only about 8 inches away and move it slowly like a paint gun.

Other than that, I guess it's important that the car is waxed with something, I only do mine twice a year.

My pattern is to hose off the car either unfiltered or with a regular hose nozzle to get rid of the major stuff. The I do the car a quarter at a time. I rinse it good, then soap a quarter of it good, 'wash it with a new microfiber towel, then rinse with unfiltered, then do the next quarter. Once the whole cars' done I go over the whole car with the filtered. If it's so hot or sunny that the first section starts to dry before I finish washing I'll rinse those areas again to keep it wet until I've done the whole thing and am ready to do the filtered rinse.

That's it. I DO have Zaino on the car, but it's only like 3 coats and done twice a year. It's garaged at home and at work, but that doesn't mean it doesn't get washed weekly. Usually anyway.

 

I have this. I figured it would be a good way to save a little water in Old Town. It seems to work fine. Definitely easy to use, and it works with BMW/MINI soap as well as the Mr Clean soap.