I just picked up a rental car in Prague and we will be using it to visit Hungary, Austria, and Germany - barely touching into Slovakia along the way. We're doing a big loop. We are zipping quickly from city to city and will be using major highways whenever we can. Here in the Czech Republic the car has a pre-paid vignette for the motorway.
This question is just now occurring to me - do toll roads in any of these countries require some sort of vignette sticker or are there toll booths? We haven't driven roads in these countries in 20+ years and don't know what to expect now!
Thanks for your help!
Austria - Yes, you need to have an Autobahn Vignette to drive on the Autobahns. You can buy this at the border.
Germany - No, the Autobahns are free
Hungary - Don't know, somebody else will have to answer.
I'm pretty sure that, for now anyway, the Autobahn is free for passenger cars - no stickers, no toll booths. I have heard indications that that might change in the future. For Austria, certain highways require that the car have a vignette. If you use ViaMichelin to determine the time and distance between two cities, it will tell you the tolls/fee for various routes. It also has a check box to find routes without tolls/fees.
In addition to the Vignette, Austria has a number (quite a lot, actually) of tunnels which require a toll in addition to the Vignette (because they are on motorways), and at least one private toll road not covered by the Vignette.
Germany has a toll tunnel somewhere up north (I think around Hamburg), but that's it. There's plans in the works to start a vignette system, but they have not yet implemented it. No additional costs to drive on any roads.
Austria- as mentioned previously.
Hungary... I don't know the exact details, but it's some kind of registration/vignette system.
Both Hungary and Slovakia require you to buy toll vignettes near the border in order to drive on the faster roads within each country.
http://www.ricksteves.com/travel-tips/transportation/driving-europe-tips