[su li]

Whats the weight saving by the carbon fiber roof vs. Common roof?
If anybody knows please give a short answer.

 

[Mauer08]

Porsche hasn't outlined the official specs around the Exclusive model yet. On something like an M3 a carbon fiber roof saves about 10-20lbs. It would obviously be more on anything with a sunroof.

 

[Sp33dster]

Don't know what the numbers are officially, but a lot of people online are suggesting around 4kg of weight savings. For the same money that Porsche is charging you could probably cut more with an aftermarket carbon fiber hood.

 

[992gt3]

Forgot where I read it but basically the savings are so little that the price to upgrade can be a massive turn off.
Being a big part of motorsports culture, its easy to see why some people will get it regardless. Heck, even I would, just one more way to distinguish your 992 from the other guy.