Now that summer is over and it is overcast and raining much of the time it is important to turn on your headlights. It is very difficult to see other drivers in poor visibility conditions when their headlights are not turned on.
Some people turn on their running lights. But, running lights do not put your tail lights on and are not very bright in the first place.
People in blue, gray or silver cars are very hard to see in rainy conditions, they are the color of the wet pavement.