Originally Posted by Slow*Jim
Interesting! I have never heard of a car working this way
eh? it's how all projector HIDs are supposed to work.
I know people used to call high-beam headlights the "brights" but they aren't any brighter than the low beams. The difference is in the aim point. With sealed beam or halogen/reflector housings, the bulb has two filaments. the filament for the high beams is right in the focal point of the reflector and throws light as far down the road as it can. the filament for low beams is moved slightly outside of the focal point, effectively "pointing" the headlamp beam downward so you don't blind drivers of oncoming vehicles.
with HIDs, you only have one light source (the HID arc) and you can't dim it, so high beams are the HID arc behind the projector lens, and for low beams a shutter moves into place to cut off the top portion of the light beam to keep it out of oncoming drivers' faces.