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From: http://lighting.mbz.org/faq/#overwattage The marketing types like to brag about how the light color of HID headlamps has been "specially tuned to mimic the sun". In actuality, the light spectrum has *not* been "tuned" to anything, aside from tweaking the gas and evaporated-salts mix to conform to regulatory definitions of "white light". The bluish tint is a side effect of using an electrical arc as the light source. This color is quite good to drive behind, but is vastly more likely to cause glare to oncoming drivers (overstimulation of Retinal Purple in the human eye by this very color range absolutely FOOZLES night vision for a long time after relatively brief exposure). In fact, it was law in France for many years that headlamps had to produce light with substantially LESS output in the blue frequency range where HID lights are particularly strong, specifically to reduce glare to oncoming drivers. A backlash has already started in Europe, where drivers are complaining about being blinded by BMW's overloaded with a trunk full of beer. Unlike US and Canadian regulators, European regulators recognize the danger presented by excessive headlamp glare, and so European cars with HID lamps MUST have dynamic headlamp levelling. On-the-fly headlamp vertical aim adjustment has been required by European directives for quite some time now, but dashboard dial control of the vertical aim has been acceptable. No more! Recent European regulations require that the headlamp levelling of HID-equipped cars be linked to the suspension system of the car so the lamps don't glare as much to oncoming traffic when the rear of the car is loaded-down or the car is heading up a small hill. ------------------------------------------------ To unsubscribe, E-mail to: <type3-off@vwtype3.org> For more help, see http://vwtype3.org/list/