We wash our car about three or four times a year, usually at a commercial wash that recycles/filters water.

Today I just backed it out of the garage into the drizzle, wetted it down, used a wetted soft cloth to gently wipe away dirt, and used two gallons of our emergency water to rinse off.

No soap, zero environmental impact. All drains lead to habitat!

And refreshed water in some of our emergency stock. . .