OK. Here's my take on halogen vs HID.
First off I'll qualify myself. I drive highway plow in the Canadian Rockies. I drive in conditions regularly that most of you wouldn't dream of driving in.....
The real problem, as has been pointed out in this thread several times, is the plastic lenses. They fog up, haze over and pit from the sandpaper effect until they are essentially useless. They may haze up from halogen heat faster than HID but I could care less. The headlights on a highway plow never last that long anyway. Good old glass stands up much better to the sandblasting effect than plastic. It also stands up to the heat better.
Having said that, halogen puts out more heat than HID because there are 55 watts vs. the 35 watts of HID. That would also be 55 watts of light output vs 35 watts HID. The halogens have a better spread of more light for more peripheral vision and recognition of road (or off-road) hazards, wiped out, stranded cars and wildlife. More heat from halogen also means less ice and snow build-up, especially glass vs plastic. We have found that HID requires far more stopping and cleaning headlights. No thanks.... We have started using LED brake, marker, turn and running lights and after a very short time they virtually disappear...., but they don't have to be changed and dissipate light better than regular bulbs. LED headlights in snow and cold...?
HID do work better in fog and blowing snow but only in low beam and only because they put out less energy thus less glare.
My biggest complaint about the HID's is the lack of peripheral and the lack of heat resultinging in more icing.
Sure wish there was a glass headlight option for a Touareg.:roll: