caf

Fog lights are kind of a pet peeve with me. They're FOG lights, not "driving" lights. Every Honda and Pontiac on the road go driving around with them on all the time, as sort of a fashion statement. Fog lights reduce glare from fog by three mechanisms:

1) They're located below the visual axis, so the light is reflected less directly off the surface of water droplets in the air.

2) They use a more diffuse, less focused beam of light to also reduce reflection back towards the driver. They really provide little useful light forward under normal driving conditions.

3) The color of the light can also be used to reduce back-reflection (yellow lenses, for instance).

I do agree that they sometimes help illuminate the side of the road. Most modern halogen and xenon lighting systems, while very bright, are very poor at providing light outside the central coverage zone. This is due to the fact that the very bright light beam would be blinding to oncoming traffic, and the fact that the projector systems are simply not very well designed, but that's another topic.

Likemystoppie?

If they were true 'fog lights' they'd be of a yellow or amber color. White light doesn't do well in fog like conditions, it reflects too much. They are by no means 'true' fog lights. They're more asthetic and help fill in that gap between the lower portion of the headlight 'beam' and the front of the car with light.

Car company's call them 'fog lights' b/c it's easier for customers to comprehend as oppossed to calling them 'driving lights'.

More often then not you'll get a blank stare when you refer to them as 'driving lights'.

Edgy01

Years ago Porsche's 'fog lights' were available from Robert Bosch with driving lenses,--instead of the usual fog lenses. I swapped them in and seriously augmented my H4s. At other times of the year I would return the fog lenses to them. Through some special wiring I could get them to work either with or not with the headlights. I suspect the Porsches going to France may have amber bulbs in them.

DrDrilZ

i have the hoen bulbs and they match the xenons much better thatn the yellow stock bulbs. however, they are not as bright. at leat the hoen are rated the same wattage as stock. be careful with other bulbs that have a higher wattage than stock.

caf

Not trying to be difficult, just not sure I'm following you...

Fog lights can be yellow, or white, and they certainly are designed as fog lights, at least on European cars. Porsche calls them foglights as well, and has the front and rear foglights switches grouped together. I don't think the rear foglight is a rear "driving light". Are you saying that Porsche really intended for these to be driving lights, and calls them foglights because they didn't think we'd understand that they're really driving lights? And they added the rear foglamp just to complete the illusion?

I don't have any gap in light coverage in front of the car before the regular headlight coverage that needs "filled". I can't think of any car I have where I see darkness immediately in front of the car from the driver's seat before the regular beam coverage begins. Is that what you're talking about?

Likemystoppie?

Quite simply: When you use 'white' bulbs for fog lights, they reflect back at you more. They are NOT effective in 'foggy conditions'. As I said before, a 'true FOG LIGHT utilizes either yellow or amber bulbs-this colored light penetrates the water vapor as oppossed to being reflected off of it and back at you-so you can see the road ahead better. And the reason the rear fog light is RED is because you can see it MUCH father away when approached then you would if it was a 'white' colored bulb. Rear Fog Lights are always red, (some time in older cars you'll see an amber, but this is rare) to represent a brake light....warning others and showing the position of your car..... THUS supporting the fact that it is indeed a FOG LAMP. And yes, Porsche calls them, as do most auto makers 'fog lights' because the general population would get confused with calling them 'driving lights'. People would consistantly say "Aren't the headlights the driving lights?"

So in reality, the Porsche cars have front driving lights, that enhance and boost frontwardly vision when driving, and ONE rear FOG LAMP in the rear. The rear being fully functional and I suggest people use it every time it rains (or snows). And actually, if you just sit in a lot of cars, turning the headlights on, and then the front 'fog lights' you'll notice that these lights 'fill' the dark area between the the lower edge of light from the headlights and the point below that and around the corner of the car. This absoluely depends on the make and model, of course. My Mercedes is a perfect example; the light from the front driving lights I use all the time to enhance and fill the area that isn't normally filled via the headlights. Enhanced night driving is the result. The same was said for my BMW's, and also my Acura.

And in addition, when riding my Motorcycle, I bring along one "amber" plastic lens that goes over one of the headlights when I get caught in rain. It gives MUCH better night driving in the rain, allowing me to pick up on the yellow lines and street signs hands down ten times better then with 'white bulb' light.


At the end of the day it doesn't matter what you call them; all you have to do is test out the various colored bulbs in the bad weather and good weather and you'll find out exactly what I'm saying.

gmoney99

Great option is the Hoen Endurance, yellow for true fog use
www.hoen-usa.com/endurance.htm

Pretty much every car co. has turned fog lamps into auxilary lighting, a cosmetic thing vs. true use in fog. Roads are much better lit nowdays, even in Europe, at leasts thats their excuse. Allows them to go a little wilder on front end designs not having to worry about integrated true fog lamps. Its very hard to get a wide, low beam out of reflectors with clear front housing on todays cars. Look at the old Pcar lamps and marschall lamps etc. had reflectors with special designs in the front glass. Sure they were ugly but they worked!

Avoid PIAA, avoid ebay bulbs. Hoen, Narva, Philips all make quality products that would be at home in the Porsche.

jhbrennan

Owner's manual starting at page 266 is pretty good. At least that's where i got my info.

ronmart

FWIW I have Xenon's on my Mercedes and in 6.5 years and 73,000+ miles, I'm still on the original bulbs (knock on wood) - however, I've replaced a bunch of the halogens (including one DTR that is out right now). It has been my experience that the Xenon's are pretty resilent (same with the Lexus - it is 5+ years and running with no replacements yet).

caf

OK, I don't know about you, but my ineffective white fog lights reflect back far less light to my eyes in the fog than my low beams or high beams. Try it some time. Maybe we have unusual fog here. Living in a low, river valley I drive in morning fog a lot.

icon

last time i try that!
went to my favorite twisties last night to try the fog lights idea . . .
the whole area was blanketed in FOG!

Likemystoppie?

Ya, it works with 'no fog' conditions with the white lights. The other thing I forgot to mention was that the amber or yellow lights have a shorter wavelength, thus the beam doesn't go that far at all. It's meant for 'just infront' of the car.

Be careful!!