Vortex generator? Mystery windshield lip

[orange4boy]

I'll do some tuft testing to find out. I only did one side so I can compare the two.

[robchalmers]

They're a mix of NVH supressing aids and and rain deflectors, the polo has them and so do the Bentleys - heck the current SEAT Leon/Toledo/Altea have the windscreen wipers there to act as rain deflectors and wipers for aero reasons (i'll try and find pics)

on the polo they work great at highway sped I can have the wind down an inch or two when its raining and there's no swirl-round

[aerohead]

Originally Posted by SVOboy

Did Hucho say anything about how bad they are aerodynamically?

They're a concession to visibility in inclement weather.They don't cause flow separation so they are no real detriment to drag,and they allow you to see through your sideview mirrors rather than see rain trailing continuously across the glass.

[Hermie]

I'm fairly certain those are to direct airflow up over the roof for better aerodynamics. The sides of cars are notoriously unaerodynamic, with door handles, mirrors, and non-flush windows and door frames.

My advice is to not block them.

There are similar rails on race cars to direct flow better for improved airflow.

[Cd]

I did a tuft test of my Civic, which has them too. They are even more pronounced on my car, and I thought for sure that they channeled air over the car.
Much to my surprise, the air smacks right into them and keeps on going towards the sides of the car.
They certainly do not help channel air over the roof as I thought.




I had a really good straight on shot of this effect .... but I deleted it ( smack ! )

[Cd]

Note what happens on the window above the folded in mirror :

[gone-ot]

...I'll bet you get quite a few wierd "looks" when you drive by with all those tufts fluttering in the wind (I've worked in wind tunnels before).

[orange4boy]

Just yell "CARNIVAL" out of the window and honk your horn!

I tested mine the other day and got the same result. A little less tuft flutter on the delete side. It's a rain deflector like aerohead and BB say. I noticed a lower wind noise on the highway on the side I deleted mine from. Have yet to see how they change the rain pattern.

I also removed those tinted "rain deflectors" (spelled p a r a c h u t e s) that the previous owners installed. I always hated them. Now I can crack the windows on the highway and not be deafened by the turbulence. I can live with a few rain drops.