Just to clarify with the low beams on & the fog switch on you have the 80 watt low beam element in the new lamp running. The low beam part of the lens has a big cut off so it is good for fog.
Put on the high beams & the 100 watt element is running.
If you want to get real crazy you could even keep both the 80 & 100 running in the high beam mode.
As someone said, these cars do not have fog lights on them stock, they are driving lights. Fog lights are orange or yellow, reason being that white colored fog or haze will not reflect a yellow or orange hued light back at your eyes, thus penetrating the fog better. White lights will reflect back to your eye and just make the fog look thicker.
Here in New Jersey it's illegal to have fog or driving lights that are not relayed so that when the high beams are engaged they turn off. You can't run your fog/driving lights with the high beams on. I got nailed for this on my Jeep Wranger a few years ago, I had a nice set of Hella's on the front and did not have the relay installed, had to go back and put it in before they would pass me.
I thought it was that fog lights are for others to see you, and driving lights are for you to see other cars (and the road ahead). It is popular in Europe to have a fog light on the rear of the car too.
Color of the lights isn't really a factor. Fog lights could be clear (white) too.
Also, in a lot of places, driving lights have the same rules (or laws) as high beams. You are suppose to turn off ("dim") your driving lights when another vehicle approaches from the opposite direction, or when you are following behind another vehicle. It is really rare to find anyone following those laws.
Yep, a few European car makes that get imported here to the US still come with those rear mounted fog lamps, which are usually red and just as bright as a brake light. My Volvo 850 has one, and a switch on the dash for it. Off the top of my head I know Porsches and Audis have them also. It's only supposed to be on one side though, if it were on both people would think you had your brake lights on all the time. On the Volvo forum I frequent, a guy rigged up a second rear fog light on the other side, I guess having only one upset his sense of symmetry and balance. He got pulled over for it, the cop told him he needed to get his brake lights checked because they were on all the time.
I wonder sometimes why manufacturers still put high beams on cars, there's so much traffic in my area I could count on one hand how many times I've had the chance to use them in a year. All they seem to be good for these days is visual horn, like flashing someone when there's a cop down the road.