Last weekend I travelled from Koper in Slovenia through to 's-Hertogenbosch in the Netherlands, using the weekly car sleeper train which operates in the summer. The train was formed of 8 coaches, including sleeping cars, couchette cars, and a restaurant car, plus 6 double-deck car-carrying vehicles. From Koper we had a Slovenian 541 class electric loco through to Jesenice via Ljubljana, hauled from Prestranek to Ljubljana by an OBB class 2016 diesel (because of the overhead wire damage caused in the winter). Because of engineering work between Jesenice and Villach, the train took the diesel only route via Klagenfurt, so a further pair of OBB class 2016 diesels worked on that section. These were replaced by an OBB 1116 to Salzburg, where 1142 704 (owned by CBB) took over and worked via the north side of Munchen, south side of Frankfurt, across the bridges at Mainz, the left bank of the Rhine, avoiding Koln Hbf, and on to Kaldenkirchen, a few kms short of the border at Venlo. Here the 1142 had to be replaced by a class 189 electric for the short trip to Venlo, as the 1142 is not licensed on NS rails. Finally a "Baldwin" class 12 took over for the run to 's-Hertogenbosch, where the arrival was on time.
The operator of the weekly trains from 's-Hertogenbosch to Alessandria, Livorno and Koper is
http://www.autoslaaptrein.nl/
Bookings can be made and paid for in Sterling via their UK agents, Railsavers
http://www.railsavers.com/
Prices vary according to type of accommodation, and season.
They accept passengers without cars too (like me). Certainly worth considering, either for a family holiday (with or without your road vehicle(s)) or just as a single traveller.