Why are car fog lights all white now?

[WilliamFitz]

Car fog lights are all white because white light has the highest brightness. Function of car fog lights: The purpose of rear fog lights is to make the vehicle more visible to drivers behind in conditions of low visibility such as fog, snow, rain, or dust. Precautions for using fog lights: Car fog lights can increase visibility distance, improving the visibility for the driver and other traffic participants, allowing oncoming vehicles and pedestrians to spot each other from a greater distance. Under normal circumstances, fog lights should not be used; they are only necessary in thick fog. Even in heavy rain, only low beam headlights are needed, as fog lights do not provide any additional assistance to the driver.

[LeGabriella]

Having driven for fifteen years, I've noticed that fog lights have mostly turned white nowadays. Actually, the popularity of yellow fog lights in the early days was due to their better penetration, making them suitable for thick fog conditions. However, with technological advancements, white LED light sources offer high brightness and low energy consumption, and their penetration in rain and fog is no worse than yellow light. Naturally, manufacturers prefer this more cost-effective solution. Additionally, regulations have loosened, with both the EU and China now permitting white fog lights. To be honest, white fog lights coordinate better with daytime running lights and look more modern aesthetically. I've observed on highways that white fog lights actually provide longer visibility in light fog compared to yellow ones, especially on reflective wet road surfaces where they stand out more. However, in heavy fog with visibility below 50 meters, veteran drivers might still miss the gentle penetration of the old yellow fog lights.

[SanElla]

White fog lights are really common on the road these days, which ultimately comes down to technological advancements. The earliest halogen fog lights required yellow filters to display color, adding extra costs. Now, LED modules directly emit white light, making them cheaper and more durable for manufacturers to produce in bulk. Moreover, white light has high visibility in rainy weather—when driving on the highway at night, you can spot the outline of a car's white fog lights from far away. In terms of regulations, most countries have relaxed restrictions on fog light colors as long as the brightness meets standards. I think another reason is aesthetics—white fog lights paired with today's streamlined car bodies look much more stylish than old-fashioned yellow lights. However, a reminder: if modifying fog lights, avoid using ultra-bright cool white light, as it can easily create glare in fog and impair your own vision.

[DiEliza]

From an optical perspective, white fog lights are actually a comprehensive choice. People often say that yellow light has better penetration, but this actually refers to specific wavelengths (such as 560nm) having strong penetration. However, modern LED white light is generated by blue light exciting yellow phosphors, which inherently includes the wavelength bands that penetrate fog. When you turn on fog lights in heavy fog, the yellow component of the white light can still penetrate the fog, while the blue component enhances close-range road illumination. Moreover, in modern urban environments with streetlights, white fog lights create greater contrast against gray backgrounds, improving warning effectiveness. Manufacturers also save on the process of adding yellow filters, and the battery load is lighter. In cases of extremely heavy fog, using hazard lights is more practical than worrying about fog light color.