There is a car wash in my area that uses foam brushes. Not really sure if this is more or less destructive than the spinning cloth brushes. I'll have to check it out. Otherwise, it's $25 for a hand car wash. $35 for an SUV.
I know that from your post, you can't wash the car at home in the winter...but this site has some great info on car washing: http://www.detailingspot.com/?page_id=15
They are all destructive to a degree. Even a hand wash is bad if the proper technique and wash mitts aren't used. Foam/sponges to hand wash a car hold the dirt particles against the finish more than some other materials.
If you have a white car....the minor scratches and swirls won't be visible though.
Disconnect the cold water spicket on your washing machine and install a splitter so you can hook up your garden hose and run it out to the driveway and wash it by hand. Kinda cheesy but it would work.