Been driving for 40 years. My 6 month old Prius is my first car with fog lights. How are they meant to be used?
I don't use them as they don't add that much light and are designed to work only when the headlights are on (unless you do a mod).
<div class='quotetop'>QUOTE(lenjack @ Jun 5 2007, 01:46 PM) [snapback]455978[/snapback]</div> When you're driving in foggy conditions and have your regular headlights on, the fog usually scatters the beam. Fog lights are meant to shine under the fog, where it is thinner, providing a greater illuminated distance than what would be provided when you use your regular headlights alone. So, in short, they're meant to be used when it's foggy outside.
<div class='quotetop'>QUOTE(lenjack @ Jun 5 2007, 04:46 PM) [snapback]455978[/snapback]</div> I actually replaced mine with real foglights because I was so depressed by the lack of functionality of the stock ones... but to the point, you are only supposed to use them in fog, snow, heavy rain, or whenever you need extra lighting.
They aren't actually fog lights. They are just secondary driving lights. To be fog lights they would have to be tighter focused, much brighter, and have the ability to be used without the regular headlights on.
They are supposed to light up more of the road right in front of the car and to the sides, so you can see better crawling along in fog and snow. The one's on the Prius are mostly decorative, but they help a little in bad conditions. Tom
And just a note to all. "Real" fog lights as described by John are illegal in most jurisdictions. Ditto for "driving lights". Headlamps must be on when "aux. lighting" is on. Hence the way the Prius, and any other legal car is wired. I've read reports of tickets given out in Oregon, Washington St., Montana, and Idaho for "fog lights" without headlamps. But as always, YMMV.
<div class='quotetop'>QUOTE(David Beale @ Jun 5 2007, 10:40 PM) [snapback]456238[/snapback]</div> That's true, and 'proper' fog lights are designed to be used as supplemental lighting rather than replacements for standard headlamps. BTW, had to drive in fairly thick fog in my Prius last night - the fog lights are quite effective, creating better vision and visibility without a lot of additional glare.
<div class='quotetop'>QUOTE(ZA_Andy @ Jun 6 2007, 05:37 AM) [snapback]456445[/snapback]</div> Is that with or without the headlights on?
Most, if not all places, they are illegal when used with high beams. That is why you cannot use them with high beams as supplied from the factory. Legal with parking and low beam only.
They are real foglights, it's just that the US version, for whatever reason, doesn't let you use them with the headlights off, greatly reducing their usefulness. Here in Europe, they operate with the headlights off, and do the job they're intended for - picking out the kerbs and lane markings while travelling at low speed, with the headlamps off to reduce glare, in extreme fog or snow conditions.
<div class='quotetop'>QUOTE(Tideland Prius @ Jun 7 2007, 02:05 AM) [snapback]457187[/snapback]</div> On, low beam.
<div class='quotetop'>QUOTE(KMO @ Jun 7 2007, 07:11 AM) [snapback]457245[/snapback]</div> It's illegal in most parts of the U.S. to use fog lamps without headlights. That's why the Prius won't let you run them separately. Tom
<div class='quotetop'>QUOTE(KMO @ Jun 7 2007, 01:11 PM) [snapback]457245[/snapback]</div> Not in whole EU... probably depends on the local law. It is illegal in my country and fog lights can only be on when headlights are on. - Piotr
<div class='quotetop'>QUOTE(ZA_Andy @ Jun 7 2007, 04:20 AM) [snapback]457249[/snapback]</div> Interesting. I can't remember if it made a difference in the fog last year. Don't think it had otherwise I might've remembered it lol. <div class='quotetop'>QUOTE(qbee42 @ Jun 7 2007, 09:07 AM) [snapback]457385[/snapback]</div> which kinda defeats the purpose of foglights