A workbench assembly that may be reversibly mounted to a trailer hitch receiver of a vehicle with a stabilizer assembly that is also reversibly mounted to the trailer hitch receiver that functions to hold workbench assembly stable and free from motion relative to the trailer hitch receiver. Workbench assembly is collapsible or foldable so that it may be collapsed and folded tightly against the back of the vehicle during vehicle travel and unfolded or extended backwards from the vehicle during use of the workbench. Workbench may have rounded edges for clamping thereto by special clamps. Workbench may have one or more locking groove in its surfaces for locking or clamping thereto by special clamps. When not in use, workbench assembly may stored or mounted on the shop wall by detaching it from the trailer hitch receiver on the vehicle and remounting to a special wall mount assembly attached to the wall.