The HID stands for High Intensity Disharge lighting. It produses like a purpleish blue lighting effect. They are really bright. The beemers heve em on. There is an HID kit for the scort on NOPi.com i think. A bit expensive.
I just wanted to clarify something about HID lighting. They produce a white light that contains more of the spectrum than standard incandescent lighting. They also produce much more light at 55watts than an incandescent bulb and are cooler running than incandescent (which rely on the heating of a filament to produce light). You can think of HID lighting like flourescent lighting. There are two electrical posts that are suspended within an inert gas. A ballast is used to up the amps and lower the volts so that an arc can jump from one post to the other (just like in a flourescent bulb), between the two posts, the electricity excites the gas and causes it to produce light. Unlike a flourescent bulb, there is no coating on the bulb´s wall to soften or modify the light. A side effect of this is a blue/purple light that is refracted off the sides of the bulbs making them appear blue/purple from the sides. HID light does not shine blue/purple light on the road.
No incandescent bulb can match them or come close because of the narrow spectrum band and the high heat.
Coated lenese (like all these cheap ´HID conversion kits´) heat up even more, since the coating absorbs light and heat. The coating does not make a ´whiter´ light. If you´d paid attention in physics you´d know that filtering light can only take away colors and that white light is a mixture of every color. Incandescent bulbs produce many colors of light.. yellow being the most prevalent (by a slim margin), meaning that their light is somewhat white. Blue coated incandescent bulbs block nearly every color but blue from exiting the bulb. This means that the light is actually less white and will wash out whatever you shine it upon.
In other words.. compare HID, to Incandescent to Blue Coated Incandescent bulbs on the same surface.. a red car.
The red car looks cherry red when illuminated by the true white light of the HID.
The red car looks a dull red when illuminated by the incandescent bulb.
The red car looks blue-ish purple when illuminated by the blue lights (the only light you shine is the only light reflected).
Many of the blue bulbs are higher wattage to make up for the light that is blocked by the filter. This makes them even hotter, which means they don´t last long and can potentially burn up your headlight housings.
Blue light also refracts much more easily within water droplets resulting in random glare. This makes seeing in fog and rain much harder. Yellow light refracts the least. This is why fog lights are often yellow.. and car lights should never be blue. ;-)