When you encounter a car in the dark, your visibility is reduced. Therefore, you should reduce your speed.

A car coming towards you reduces your visibility for two reasons:

You cannot use full beam headlights when approaching another car. You have to rely on the dipped headlights, which provide a visibility range of about 50 - 100 meters on modern cars.

The lights of the oncoming car increase the contrasts in your surroundings, making the dark areas even darker and therefore harder to see.

Therefore, driving conditions become more difficult when you encounter a car in the dark – hence, you should reduce your speed. Additionally, you should turn off the full beam headlights when you are 200–300 meters away from the oncoming car. Therefore, driving conditions become more difficult when you encounter a car in the dark – hence, you should reduce your speed. Additionally, you should turn off the full beam headlights when you are 200–300 meters away from the oncoming car.