At night on an insufficiently lit road outside a built-up area, which lights must you have on in your passenger car when traveling over 40 km/h?

Correct answer: The high-beam headlights.

At night, outside built-up areas and with insufficient lighting, traveling at more than 40 km/h requires using high-beam headlights. They must be replaced with low beams when necessary to avoid glare.

Reglamento General de Circulación (Real Decreto 1428/2003), texto consolidado