Approaching night my mother and I were on our way to Athens when we saw a UFO slowly hovering almost stopped up in the sky, not just right above us. Getting closer to its place the object started hovering further and then stopped. About 1 minute after and as we were starting to get moving past it, it started moving closer to us and the accelerating with maximum speed on the horizon in front of us. It had been visible for less that three seconds. No signs of breaking the sound limit or any fumes or trails were left behind. We were not affected or lost track of time or something. We just kept silent for a while.