Rain is falling hard enough to cut visibility and your car's daytime running lights are on automatically. Is that enough lighting?

Correct answer: C. No — DRLs can leave your tail lights off, so switch the headlights fully on

No — and the reason is one most drivers have never been told. "Your daytime running lights are not to be used as headlights during poor lighting conditions. They provide an inappropriate form of light that may cast glare onto others or deactivate other required light systems, such as tail lights." That last clause is the dangerous part: on many vehicles the DRLs light up the front while leaving the tail lights dark, so in rain or snow you are invisible from behind while feeling perfectly well lit from the driver's seat. Turning the headlights properly on brings up the tail lights, parking lights and rear licence-plate light with them. If your car has an automatic setting for the full lighting system, the Handbook recommends using it.

Source: MTO Driver's Handbook: Getting ready to drive — Turn on headlights at night and in poor conditions, daytime running lights