From visiting the NAIAS 2002 in Detroit, they look like this. The Digital Camera did not capture just how insanely bright they are. They are the same tint of pure white as a BMW's (Surprise, huh?)
They take about a 1-2 count to get to full brightness, but don't flicker like some of the early systems. Just turn on bright, then crazy bright. Apparently 25% brighter than any halogen system, but with the whiter light they look many, many times brighter than that.
The little exhibit set-up was like a MINI Science Centre exhibit. This one had a picture of a headlamp, and when you pulled a flap down, one of these snapped on, aimed at your head. Bit of an assault on the eyes.
Xenon HID Gas Lamps are standard on all the Canadian MINI's except for the first 500 pre-spec'd launch editions. Not something I would have forked extra money out for otherwise... Besides, most all of the other drivers seem to hate them. People blink back their high beams as if you were driving around with your high beams on. Maybe the MINI will be better because it's so low. Can't wait until SUV's start driving around with HID lamps, that'd be a treat in the rear view mirror.
With headlights, there are two types of beam - main and dipped. With halogens, that's usually done by having two separate bulbs and two separate reflectors, and either two lenses or one lense with two sepearate parts. The dipped beam is cut-off part way up so that the headlights illuminate in front of the car, but only so high - lower than the position of drivers in oncoming cars, or we'd dazzle them. With xenons, the main beam and dipped beams are usually provided by the same bulb, tilted up for main beam and down for dipped.
The dipped beam has an angled cut-off so that more of the left hand verge is illuminated, and higher up (here in the UK). That is caused by the lense pattern. Of course continental drivers have a different lense pattern so that they see more of the right hand verge. If we use a UK lense on a RHD car on the continent, this pattern means we'd dazzle the oncoming drivers even with our lights dipped (and vice versa). To convert a headlamp for continental driving, we have to cover the part of the lense that throws light up and to the left - hence the black stickers. For halogens.
Now from what I've been told of xenon lamps, the lense is clear - no beam pattern. Instead, the beam pattern is set by the shape of the reflector and the position of the bulb itself. Apparently, to convert from RHD to LHD patterns, theres a switch under the bonnet on the back of the headlamp assembly. Little bits of black plastic are no use at all, as the beam pattern isn't set by the lense.
Halogen drivers need plastic stickers, xenon drivers will not. At least, that's what my sources tell me, and they make the damn things so they'd better know! Are you sure the handbook is talking about the xenon lamps?