More air curtains or straight blocking bumper vents?
 

So Ive had an idea of doing air curtains through the two little vents on my Mazda Demio. Its a fair amount of work due to room constraints within the area behind the bumper so will require a fair amount of work.

Has anyone done much testing with them? I couldnt find much using the search finction but thought someone might know of external sources.
Its between air curtains and blocking off the holes which lead to no where.
I dont want to put in the effort if the gains wont be measurable or if the tyre positioning is going to make them ineffective.

https://scontent.fwlg1-2.fna.fbcdn.n...-Q&oe=641A285F

Possibly another option along the lines of the Porsche design, send it out under the car infront of the tyre? may cause lift?

I see the problem you high-lighted.

By the time you build out to the tire shoulder, you may as well make an external barge board and use the vent for brake cooling.

I'd take it with a grain of salt too, because of brake cooling.

'air curtains'
 

Just to confuse you even more, I posted a link to the 2024 Ferrari Purosangue SUV, which has the most elaborate system of front and rear air curtains I've seen on a 'production' car.
CFD would be the best way to engineer these systems, but also very expensive.
Perhaps the Ferrari will offer more grist for you to ponder.
Front and rear skirts remain the 'ne plus ultra' drag-wise, but they're not for everyone.