In an effort to reduce costs, the Speed World Challenge Touring Car Rules will restrict exotic engine builds, transmissions, and suspension set ups next season. Fields in this series have shrunk to less than 20 cars (4 or 5 BMWs including the 3 Bimmerworld entires). The dominance of factory supported Mazdas and Acuras have chased many privateers away. When the series ran in the DC Grand Prix weekend, there were close to 50 starters and over 20 BMWs.
http://www.world-challenge.com/news/story.php?ID=1146