The weight saving is amazing.

From the article:
Audi has prepared a unique Audi RS3 Sportback with several special features, including carbon fiber wheels.

About a month ago we heard VW saying they formed a partnership with ThyssenKrupp Carbon Components and Maxion Wheels to work on carbon fiber wheels which are up to 40% lighter than a forged aluminum wheels.

Photos and article - Audi one-off RS3 Sportback with carbon fiber wheels