Driving through Schengen countries crossing various borders, we knew that we have to be careful to comply with the road tax law in each country. Some use traditional tolls but many use these stickers (Vignettes) that you have to buy and display on the windshield. You can get information from many websites like this https://driveeurope.co.uk/2013/07/02/road-tolls-and-vignettes-in-europe/
One time our group was driving in two 9-passenger vans from Zagreb, Croatia to Graz, Austria on highway E59. This route takes us through a short 59 Km section in Slovenia. We knew that we need to stop at the kiosk to buy the road Vignette for Slovenia just as we crossed over the border.
So we parked the car and went to the kiosk and the seller asked what kind of car we are buying the vignette for and we said “four wheels” as I though it is the same as Thailand that the tolls are classified according to the number of wheel axles. We got the vignettes and displayed it clearly on our vans’ windshields.
Well, just before we crossed into Austria, my car, which was in front, was waved by a policeman with a pair of binocular to pull over into a roadside area. He explained that we were displaying an incorrect vignette for our van. We bought the one for a “car” where we should have bought a slightly more expensive one for “van”.
When we told him that we were sold this at the kiosk, he said that he cannot help as he has already logged us in, but he can reduce the fine as we are tourists. He said that normally he would fine Europeans 300 Euros for this kind of offense but he is going to “reduce our fine to just 100 Euro” !!!
This must be the most expensive road toll ever as for just 59 Km, we had to pay over $110 Euros of tax plus fine for each van !!!