For an ordinary passenger car moving on a highway in daylight, when does insufficient light require the headlights and taillights to be on?

Correct answer: When a person is not clearly visible at 150 metres.

Why

For an ordinary passenger car, use the required headlights and taillights when light is insufficient to see a person clearly at 150 metres. The MPI Driver's Handbook gives a shorter distance (visibility reduced to 60 metres); lights on at 150 metres meet both. They are also required during the nighttime half-hour window. In fog or snow, use low beams, reduce speed and leave more room.

Verified against Vehicle Equipment, Safety and Inspection Regulation, M.R. 31/2019 · Sections 5.2(2) to (3) and 1.1 (headlamps)