wind flaps under the car near engine ...

[Heiko]

Yes they are important - without these, there is not enough cool air redirected for cooling the engine bay.
They call them a spoiler in the parts catalog
Up to 2000 Part # 986 331 361 02
after 2000 Part # 986 331 361 03

[Jamesp]

I've seen nice ones made from aluminum but they might be easy to scrape off. just fold them up and pop rivet them on.

[KenDFW]

Originally Posted by Heiko

Yes they are important - without these, there is not enough cool air redirected for cooling the engine bay.
They call them a spoiler in the parts catalog
Up to 2000 Part # 986 331 361 02
after 2000 Part # 986 331 361 03

+1; cools temps in engine bay/transmission.