In foggy weather with a car 100 meters in front, you should use your low-beam headlights and front fog lights if your vehicle has them. You should not use high-beam headlights because they cause glare by reflecting off the fog, reducing visibility. Rear fog lights are generally reserved for when visibility drops below about 50-100 meters and are usually not recommended when closely following another vehicle, as they can dazzle the driver ahead. Hazard lights should only be used if your vehicle is stationary and causing an obstruction.

Appropriate lights to use:

• Low-beam headlights (dipped headlights) to maintain road illumination and help other drivers see your vehicle.
• Front fog lights to improve visibility directly ahead without causing excessive glare.
• Avoid high beams, especially when following another car.
• Rear fog lights only if visibility is severely reduced (less than 50 meters), and you are not closely following a car.

This advice aligns with safety regulations and recommendations from different countries and ensures visibility while minimizing glare and distraction for other drivers in foggy conditions.