There currently are a variety of options to travel by night train from Cologne (Germany) to Bischofshofen (Austria), taking approximately 10 hours: Namely the UEX 1311 and the UEX 1313. These lines are operated by UEX.
UEX (Urlaubs-Express) runs seasonal night trains and car-carrying trains between Germany and Austria.
You can choose a seat, a couchette berth, a whole couchette compartment, a private sleeper compartment or connected sleeper cabins.
Cars can be taken on the train at the car terminals only, and the vehicle is booked together with the ticket.
There is a free ski compartment. Drinks and snacks are available in the bistro on board.
Children with their own seat or bed pay a reduced fare.