That's a shame, I've used that route a couple of times, once there and did Slovenia Croatia and rode back through the alps etc. and vice versa. Got an email back from OBB:-
Dear Mr. *****,
thank you for your inquiry.
Please note that after the change of timetable (10.12.2017) the car train is not operating anymore on the route Wien-Düsseldorf-Wien.
The following connections with car trains will remain:
Wien-Feldkirch-Wien, Villach- Feldkirch-Villach, Graz-Feldkirch-Graz, Wien-Hamburg-Wien , Innsbruck-Düsseldorf-Innsbruck-, Wien-Livorno-Wien, Wien- Verona-Wien
Dear Mr. *****,
thank you for your inquiry.
Please note that after the change of timetable (10.12.2017) the car train is not operating anymore on the route Wien-Düsseldorf-Wien.
The following connections with car trains will remain:
Wien-Feldkirch-Wien, Villach- Feldkirch-Villach, Graz-Feldkirch-Graz, Wien-Hamburg-Wien , Innsbruck-Düsseldorf-Innsbruck-, Wien-Livorno-Wien, Wien- Verona-Wien