I doubt they're the worst, but driving in Greece was quite the experience. People just stopped in the middle of the street and park there to run in somewhere, the cars behind them just move into the oncoming traffic to get around, drivers would just make new lanes if they think they have a few inches clearance, and in several places the two way roads were not wide enough for two cars. You had to not be too tentative trying to make a turn or get in a lane, because the drivers behind would just start pulling around you. I read Greece is one of the more dangerous countries in Europe for driving. I would do it again though, no hesitation.