On the GT3 RS the wing is there for homologation purposes too, as this road car is the basis for the racing 911s.

On the various basic GT3s, I'm not sure if it is really needed, as the normal Carrera S is as fast and the absence of the fixed wing isn't thought  to impair speed or safety. The 997.2 is as fast as the 996.2 GT3 and the 991 is as fast as the 997 GT3, but Porsche haven't thought necessary to add a wing to the newer models. Same with the optional Carrera Aerokit that is a copy of the GT3 aero-system. Is the Carrera S unsafe without the Aerokit? Porsche would have been irresponsible if that was the case.

Of course, if you do near Vmax speeds for long distances (like in autobahn driving) the downforce of the wing will help stability in various situations, like in cross winds etc.


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"Form follows function"