Rear Air Curtains from KIA?
 

So Kia Redsigned their hybrid kia niro with a new body style for 2023 and increased its mpg, especially on the highway

they mentioned one of the new changes was a '' c pillar air curtain''

any thoughts on this and how it works?

I would think it is similar to a ducted Kammback.
It appears to be ducting air into the wake, but here on a much smaller scale than a full Kammback.
https://ecomodder.com/forum/attachme...1&d=1677086680
https://ecomodder.com/forum/attachme...1&d=1677086680

Wouldn’t a sharper inward angle with a hard separation edge also just help push my air into the wake? Wouldn’t the ducted air going into the back of the way still have to detach from the backside of the bumper and still create that suction cup effect or lift?

Not sure I understand.
In the example illustration above, if that duct was plugged up, all of the airflow would follow the side ot the Kammback, and exit at the edge, spilling into the wake just like the design with the duct.
The only difference is the amount of air that would be turbulent.
The illustration was just a doodle. The angles are all off, and the air would most likely not remain attached on the edge just before the 'duct'.
The idea is an attempt to get this same effect :
https://ecomodder.com/forum/attachme...1&d=1677106987
https://ecomodder.com/forum/attachme...1&d=1677107006

'air curtain'
 

KIA calls it a D-Pillar 'Air Blade'.
It will only be used on the Niro.
Not on any other KIA / Hyundai ? Genesis.
No specifics are given for it's performance.
CarSceneKorea did a You-Tube video road test with the duct open, then closed.
It indicated a 2.8-mpg improvement ( 4.2% ).
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* My impression is that the plastic cladding was furbelow.
* It may, itself, have been responsible for the drag, due to an enormous hard-edged, forward-facing step that it creates behind the rear doors, triggering a pressure-spike-induced separation overshoot at the D-Pillars, with no reattachment in the adverse pressure gradient.
* By 'ducting' the area, the CFD / Wind tunnel team may have been able to mitigate the stagnation spike there, and get the boundary-layer to settle down.
* Maybe around Cd 0.315 without the leakage, Cd 0.29 with it.
* It would be a way to 'save the styling,' which according to KIA was the reason for the 'Audi R8-esque' contrasting surface.

Allows the Aerodynamicists to slightly boat tail the rear of the car while also letting Styling have what they want with the buttress c-pillar element. Styling and Aero can often be at odds. How it works is simply the more additional air you can infill into the base area the better for drag/efficiency.

Props to aerohead for using duckduckgo.com/?q=furbelow&ia=definition

But I'd characterize it as a bargeboard:

'sharper inward angle'
 

* The physical parameters necessary for the development and maintenance of attached flow cannot vary too far from where we actually find them.
* If you look around, you may discover successful 'shapes' used by others to achieve low drag.
* For the necessary attached flow, any 'angle' measured, will be strictly dependent upon it's location along the continuous, uninterrupted, graduated curve of such shapes.
* The amount of body elongation determines the 'limit' as to how much of the contour will exist, and by default, the maximum 'angle' which can be realized.
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* If you have a straight-edge, in excess of the length of the Hyundai, if mounted parallel to the centerline of the car, you should be able to examine where different locations of body camber began, and how 'evolved' the curvature is, say, from the rocker panels, to the roof, and each of these contours will define how far you can go at each elevation, ascending from bottom to top, as if drawn out into space with an enormous french curve drafting instrument.

I used redwood benderboard.

https://ecomodder.com/forum/member-f...8-100-0625.jpg