Do you have any advice on the best route. The car train from Bled to Most na Soci sounds wonderful. Is there anything that I should know, or can you suggest any website for more information. It will be my first time in Slovenia en Croatia.
A short distance from Bled, there's an expressway to Lubljana that circles the city and then heads east toward Croatia. I've driven it and it's a nice road. There was no toll on the Slovenian portion when I drove it, but there was a toll on the Croatian portion. It goes clear to Zagreb, and actually beyond. If you're heading south in Croatia (e.g. to Split or Plitvice), there is an exit for a local road that will take you to Karlovac without going via Zagreb. That's how I went on my way to Plitvice, but I used the expressway coming back from Zagreb to Lubljana. You should be able to map these routes on viamichelin.com.