Replacing old P21/5W halogen bulbs (the double-filament ones, often used for parking lights and daytime running lights) with LED versions is a very common upgrade. Beyond aesthetics, there are also some very specific technical and safety reasons.

P215W LED Lamp For Conversion Of American Cars Position And Indicator Bay15d.

Here are the main reasons to take the technological leap:

1. Visibility and Safety

LED lamps emit a much more intense and defined light.

High contrast: Cool white light (usually around 6000K) is much more visible during the day than the yellowish light of halogens.

Instant on: Unlike a filament that needs to heat up, an LED reaches full brightness in milliseconds. This is vital if the bulb also serves as a turn signal or brake light, allowing those ahead or behind you to react more quickly.

2. Energy Efficiency and Heat

Halogen bulbs waste about 90% of their energy as heat.

Lower consumption: An LED consumes a fraction of the watts of a halogen, reducing the load on the car's electrical system.

Plastic protection: The constant heat of halogens can, over time, bake the reflector or yellow the headlight's clear plastic. LEDs operate at much lower temperatures.

3. Longevity

While a P21/5W halogen bulb has an average lifespan of around 500-1000 hours, a quality LED bulb can last over 30,000 hours. In practice, once installed, you likely won't need to replace them for the entire life of your car.