Car headlights reflect on the road in the scattered way they do because of the total internal reflection happening between the road and the glass or mirror on the car's surface. When light from another vehicle's headlights or ambient light sources hits the surface of the side mirror at a specific angle.

it undergoes multiple reflections within the glass or mirror material. Total internal reflection happens when the light strikes the boundary between the glass and the air at an angle greater than the critical angle for that material. The result is the weird scattering of light you might see on the road ahead of a moving car that may end up further distorted by wet surfaces as we've established previously.