I've halogen headlights on my Mk4 Focus and notice that when cornering or using my indicators (yes I'm old school and actually use my indicators) the LED fog light comes on for the direction I'm turning or indicating. I know this is a 'feature' and supposed to bring benefits, but I really don't notice any extra light that helps with vision, it only lights directly in front of the car and a tiny bit to the side, barely visible from in the car.
My Mk3 Focus didn't have cornering lights and I used to comment on other cars with them, saying how daft they were. Eg. when going straight on at a roundabout, the slight left turn as you join the roundabout turns on the fog light and it can, in the moment, be mistaken for an indicator, so someone thinks you're turning off the roundabout and pulls out in front of you. A minimal risk I know, but I've been in that position a couple of times with other cars.
Interestingly I didn't notice the cornering lights for the first month I had the car and I'm sadly quite interested in headlights, so thought I'd have noticed it. I only started noticing after I was fiddling with the fog lights turning them on to test them. Gives me some hope I may be able to turn them off, but suspect this is a 'safety feature' that I'll have to live with? There's no mention in the owners manual of how to turn them off.
Also aesthetics wise it's lovely blue LEDs that show up the yellow halogens even more
Does anyone know if it's possible to turn the fog light cornering lights off and if so how?