puhekieltä In a stable or garage, a place in the floor prepared so that carriages or automobiles may be washed there and the water run off.
1916, Horseless Age: The Automobile Trade Magazine
Washstand in an Electric Garage. (..) In a few garages arrangements are made for washing cars in any position on the storage floor, so that it is not necessary to move them on to and off the washrack.