Living in the bay area... let's see.
I can't wash my car with a hose at home, because 1) I don't have a home, and there aren't any hoses or spigots available at my apartments, 2) even if there were, I can't be doing car stuff like that in the parking lot of my apartment, and 3) even if I could, it's somewhat illegal to wash the car yourself. (You need a nozzle on the hose, and you need to ensure that no runoff gets anywhere it's not supposed to get.)
I guess 4) is that I know that it's a waste of water, especially drinking water, with the drought as bad as it is.
I could use some sort of soap and water bottle setup, but my car gets too filthy for that to be a reasonable solution.
I can in fact go to a do it yourself car wash place. You pay quarters, they give you time with water and soap and a shop vac. The problem, of course, is twofold: 1) just as before, I would not get to wash under my car; and 2) with the amount of time it would take to do a proper wash, the quarters consumed equal a car wash.
Or I can pay like $8 to drive through a car wash, which recycles its water, and costs about as much as the quarters to do it myself would be. I don't care about my paint getting a bit touched up.
$15 gets wash + vac + various shines. Tire dressing, rain-x, and so on. I can do the various shines myself, because I know how and what.
Meh. It's not an outrageous price... in this area and considering the circumstances.