Originally Posted by cula
I don't know, because of the heat. Somebody said that 55W HID has a higher temperature output than the 55W halogen. Well, I guess they were wrong.........
May be thinking of the color temperature of the bulb - I believe HIDs have a higher color temperature than halogens. The halogens are somewhere around 3,000K, while HIDs are higher
Check out the discussion on color temperature on wikipedia, probably more information than most people can stand (or understand) but it gives you a reference. http://en.wikipedia.org/wiki/Color_temperature
While surfing, I also found this gem on the various automotive lighting standards.