Traverser

Does this serve any purpose? Always wondered why it was there.

Max Blast

Having taken that panel off on both sides and found no A/C or heat ducting that it hooks to, I'd say not really. Probably just a vent to prevent pressure buildup under the panels and cargo floor.

chassis

Cabin air extractor?

expl0rer

There are electrical modules behind the panel on the right side. On the left not much besides some plumbing for what looked like AC for third zone, and maybe a few other things but not nearly as busy as the right panel.

I'd think both vents are there to avoid condensation building up behind the panels, as there is plenty of padding and foam as well. I would hate to have mold and wet padding or electrical components back there.

E55Greasemonkey

Probably to release cabin air pressure when closing the doors, and also for cabin air to exit when running the A/C. Behind the corner of each bumper are two grills with rubber flaps to let air escape. Without those grills you pointed out, there's no way for air to get to those vents.

Misha_

I have 3 Zone Climate control on my GL. I will check if I get air out of those grills tomorrow. If so, then it is just to accomodate cars that have that most likely.

expl0rer

Like Max mentioned, there is no ducting behind the panel. I mentioned plumbing, by which I meant tubes for the 3rd zone AC compressor. I realize now that my choice of words would be misleading.

Max Blast

I think @E55Greasemonkey is closest to the mark here. Large volumes of air need pushed out the reed valves in the quarter panels when doors are closed.

also helps humid hot air from settling in the bowels of the car, which helps prevent corrosion.

Traverser

Thanks, all. Very helpful answers. The vent idea makes sense. I notice that when I shut a door, I hear air escaping near that area.