Fog light area - anything to be gained?
 

I've seen mixed opinions on the fog light area - either a pocket forms, causing air to go smoothly past it (here) or the area is crucial to get the air back up to speed again and should be smoothed out (here).

Soooo is there any consensus on this? I'm asking because I have blinds that cover the area where the fog lights are (car is Mk2 Ford Focus). It does not leak any air as the blind is a one piece of plastic, but it may introduce turbulence. Is there anything to be gained in this area by making these flush?

http://www.european-parts.net/catalo..._fomk2fl08.jpg

It may look like it's a duct to the wheel well, but it's not - it's just a fancy dent in my bumper.

When I closed up all my unnecessary front end openings, it seems to be good for about 2MPG (estimate based on observed week to week tanks), but mine was a lot more open than yours. I had a huge front lower grill opening, medium sized upper grill opening, two side fog light openings, and two fake brake duct looking recesses, all of which I made semi flush covers for.

It looks like if you put some blue painters tape over it it will be flush with the rest of the bumper. You could try that to test it?

I tried on my HHR. Gains were negligible I think. Don't use clear box tape, though...the residue is a pain to get off!