There are four types of High Intensity Discharge bulbs: D1, D2, D3, and D4. The suffix is S for Projector Headlamps or R for Complex Surface Headlamp Units. It’s mandatory that HID bulbs are fitted with a direct replacement. D1 and D3 bulbs are grouped together because they have the ignition in the bulb, while D2 and D4 have the ignition combined with the ballast. D3 and D4 bulbs are more recent so they are designed to work with luxury vehicles, like models from Audi, Lexus, and BMW. They are more environmentally friendly because they run a lower voltage and contain less mercury.

With that said, High Intensity Discharge bulbs are only legal if the bulbs are fitted into cars that have auto leveling. This is to prevent the dazzling effect. If HID bulbs aren’t properly fitted, they can blind other motorists on the road and cause a traffic nuisance. This is not only irritating, but also very dangerous, especially when you consider the fact that people are traveling at high speeds.

HID bulbs are three times brighter than a halogen bulb, so if you thought that your stock incandescent bulbs were sufficient, imagine the light output that’s generated by a xenon white HID bulb. Their lifespan is very long, much longer than halogen bulbs. While you have to worry about your halogen bulbs going out and having to replace them, you don’t really have that issue with HID bulbs. High Intensity Discharge bulbs have a much higher luminance than halogen bulbs and produce a beautiful white light that’s very close to the color of natural daylight. This makes it exceptionally pleasing to the eyes and a much better source of light.

It’s no wonder that HID bulbs are becoming the popular choice for headlights today. As the automotive market evolves, we can expect to see more HID headlights as standard in many cars. They may even surpass halogen bulbs in the near future as more people discover that HID bulbs are the better choice.