There is a good thread on here somewhere about a procedure to wash a car with a few gallons of distilled water from the grocery store and turtle wax waterless wash. I did it a couple of times and it worked really well. I'll see if I can find the thread.
Steve
[Edit]: This thread from the other day, while not the one I was looking for, has some waterless carwash techniques:
http://986forum.com/forums/general-discussions/57980-ultima-waterless-wash-plus.html