A4 projector headlamp conversion

[TM]

Kevin,
Your question mixes three different issues:

1. European lights vs. DOT lights- the Euro-spec lights have
different reflectors and different beam patterns, that tend have
much more focused lighting and a much sharper cutoff pattern.
See Daniel Stern's site, I think it's http://lighting.mbz.org.

2. Projector lights vs. "normal" lights- the projector light
system uses a lens to focus the light from the bulb, rather than
having the bulb facing a reflector that does the focusing. I'm
not explaining this well, so anyone else more knowledgeable, please
chime in. Projector lights tend to also have a much more focused
lighting pattern, which is good, IMHO.

3. Xenon, or high-intensity discharge (HID) lights- these lights
use a high-voltage arc to cause Xenon gas to fluoresce. That is
what generates the light as opposed to electricity heating a tungsten
filament, that causes the filament to glow and generate light. Xenon
lights have been implemented both with "regular" reflector systems
as well as with projector lamps. BMW, Audi and Porsche all use projector
systems with their Xenon lighting. However, GMC, Acura and some others
have Xenon lights using non-projector lens systems. I hope that's not
overly confusing.

To answer your question more to the point, you can have combinations
of all three.

The current A-series Audis use a projector Xenon system or a non-Xenon
projector system. These can be DOT spec or euro spec. The hot "mod" for
the A4/S4 is to use the european projector housing w/ the US spec Xenon
lights. I don't think the Xenon system is different from the US or european
spec cars, just the housing itself. This accomplishes two things- (1)
apparently,
the euro-spec housing allows better light transmission to the road, with
better visibility; and (2) the euro-spec housings have clear corner lamps
with an enclosed turn signal bulb (you can't see the orange bulb except
head-on as it is enclosed in a silver mirror-finish housing, like the A4
chassis VW Golf/Jettas) so the headlamps look completely white.

I hope this answers some of your question.

Taka