If using your own car or motorhome you require a compulsory toll sticker for highways in Austria and Hungary – https://ematrica.nemzetiutdij.hu
They use cameras to spot cars without these stickers. It’s a toll you pay once. Same in Austria. Along the southern coast of lake Balaton is a highway. We never used it as the normal road is closer to the lake, but this highway brings you to the spots much quicker. Between Szántód and Tihany is a car ferry which allows a quick change to the north shore. Hungary has a number of traffic regulations it is worth checking out before you go. On the spot fines are a common way of dealing with penalties for minor traffic law violations. There is zero tolerance for drink driving and phones can only be used while driving with a hands-free kit.