I have a detachable tow bar, it is the same as the demountable Witter. If you have it there should be a panel under the rear of the car which has a silver screw you can undo with a coin. The towbar electrics can swivel down and there is a rubber stopper covering a square hole into which the demountable towbar is inserted. The bar might be under the rear floor of your car in a blue cloth bag, though I never carry mine in the car because it is HEAVY.