According to scientific theory (and practice) the above 'Pepsonian' theory doesn't quite hold water. The flaw being that light scatters, and it is most evident not in a solid or liquid, but gases - which, as far as I am aware, the atmosphere through which our headlights shine is composed of! The scientist Lord Rayleigh discovered this in the late 19th century - a very very long time before HIDs were thought of.

Scatter is what causes glare, and glare is what causes aftermarket HIDs (and LEDs) to be an annoyance.

Do a quick search on Rayleigh Scattering and you see where the issue lies. Here's a snippet from Wikipedia to whet the appetite...

Rayleigh scattering (pronounced /ˈreɪli/ ray-lee), named after the British physicist Lord Rayleigh (John William Strutt),[1] is the (dominantly) elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. Rayleigh scattering does not change the state of material and is, hence, a parametric process. The particles may be individual atoms or molecules. It can occur when light travels through transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering results from the electric polarizability of the particles. The oscillating electric field of a light wave acts on the charges within a particle, causing them to move at the same frequency. The particle therefore becomes a small radiating dipole whose radiation we see as scattered light.

Whilst I get where you're coming from and I don't disagree that YOU can see better at night with your HID headlight, we'll have to agree to disagree on the annoyance issue. I'm sure the roads are quiet at night down in Portugal, hardly any oncoming traffic, but here in the UK, aftermarket HIDs have become a real menace in the last five years, despite it meaning an MOT fail (for cars anyway).

__________________