There currently is one option to travel by night train from Zams (Austria) to Wittenberge (Germany), taking approximately 12 hours: Namely the UEX 1304 operated by UEX.
UEX (Urlaubs-Express) operates seasonal night trains, including car-carrying trains (Autoreisezüge), from Germany to Austria and back.
Options range from seats and shared couchettes to private couchette compartments, sleeper compartments and connected sleeper cabins.
Cars can be taken on the train at the car terminals only, and the vehicle is booked together with the ticket.
Skis travel free in the ski compartment. A bistro on board sells drinks and snacks.
Children with their own seat or bed pay a reduced fare.