i know over on autopia.net they talk about using zip carwash rinseless shampoo. you mix it in a bucket of warm water and wash the car. there is no rinsing needed. i have a friend that lives in a condo that has tried it and it works well for his needs as well.

its a car wash made for rv's... zip wax carwash... you can really use any of the one-step rv washes also and wash in the garage.