I always just went to one of those car wash places where you can spray your own car and took my bucket and stuff. I think there was only like two times that people came to me and said, "Hey no hand washing here." I tried to only do it when no one else was really around, so most of the time people working there didn't care.
'11 BMW E92 ///M3 - ZCP and DCT
'15 Ford F-250 - Lariat, 6.7 Powerstroke Turbo-diesel