Front bumper side vents - what do they do?

[stealthtes]

What are the purposes of the front side vents on the front bumper?

Does it help or hurt aerodynamics if I add trim guards to it, like the phone in the photo below

 

[labmixz]

If you're talking about the trim around the fog lights, it will definitely hurt the aero dynamics of the car... will you notice it, doubtful. However that is definitely trapping air and interrupting the passing air.

If you're talking about the front lip, it would solely depend on which front lip, some aftermarket body pieces can enhance the aerodynamics. Adro pieces can reduce drag, see Vendor - eas | ADRO Tesla Model Y Carbon Fiber Program released

 

[J Neptune]

Is that a vent or a plastic sticker on the bumper?

 

[stealthtes]

Is that a vent or a plastic sticker on the bumper?

It’s a vent