This was too good a story not to run it by the urban legends folks...

Turns out to be basically true with a few corrections.  It was 
Fredericksburg, VA, apparently, and the $4000 was a bit of an 
embellishment.  Here's the investigation along with the rather amazing photos:

http://www.snopes.com/photos/animals/carwash.asp

Best to all,

Brad Beukema