Opened my sunroof for the first time yesterday and was disturbed to see this plastic flap pop up into the windstream as the sunroof opened. What the heck is this thing supposed to do? All it seems to do is make wind noise; if I pushed and held it down with my hand it was much quieter.

Anyone know what I'm talking about?

 

Aero purpose + (to protect debris from coming inside the car)

 

Well that and it allows fresh air to come inside, as well as through the vents, without disturbing the cabin too much

 

removing it may make it quieter at slow speeds, but at high speeds (freeway speed) i found that the plastic piece is very important. it doesnt so much make it louder/quieter, but changes how the air flows. i pushed it down going probably 70-80mph and the sound coming in to the cabin was very annoying. almost rhythmic, but not in a good way. it felt like there was low pressure flowing past my ears, almost felt like they could pop or something. just my opinion. not sure if anyone else has noticed this.

 

It's mainly to prevent that ear popping pressure fluctuation you get on a lot of cars. You'll notice it has shallow notches in it. This breaks up the airflow and causes it to tumble in smaller chunks that largely cancel the cumulative pressure waves out. Without it the air uniformly rolls over the edge in eddies that temporarily stall right behind the front edge then suddenly collapse over and over again causing the pressure in the car to rise and fall, rise and fall.

Most cars with factory sunroofs have something like this anymore.

 

Oh damn, Im talking about the wrong thing


But yeah blkaspec and luekatron pretty much covered it

 

Spoken like a fellow Aerospace Engineer graduate...

Thanks for the info guys!

 

HEY, anybody living in a climate warm enough to open the sunroof yesterday can just go find their own answers !!!!!!!


Just kiddin'
brrrrr

 

hahahha ^ very true, its bellow freezin dude

ps. that plastic thinggy looks so cool when your sunroof/moonroof is open

 

It also prevents air/forces from peeling your headliner down at the aft sunroof opening...
And most of us know that area of the headliner isn't the most robustly attached anyway...

 

Try doing a relatively high rate of speed (45mph+) and reach your hand up and push that plastic piece back into place, and you'll find out real fast why they put that in there.

Some people claim that they don't notice a difference, but in my TL, pushing the plastic piece down causes VERY intense air vibrations to enter the car. Like very drastic pressure changes. It instantly gives me a headache.

 

some people cant really hear that low pressure vibration though. Basically more air is flowing into your car than out and your drag coefficient goes to hell.

 

They may not "hear" it but if they don't "feel" it,, they have holes in their eardrums... Because likes you stated, whether you are opening a window or the sunroof, it can result in both or either an increase and decrease in the cabin pressure - most of the time alternating very quickly.

Like Desert-TL it drives me INSANE!!