Here's more info about the series.
http://www.autoblog.com/2013/03/29/g...-racing-to-us/
But unless the domestic manufacturers enter, the series will definitely struggle a lot more. Unless all the other "non-domestics" band together to support.
As well, the market position of the cars aren't helping. More people can afford a Focus, Civic, etc.. (as raced in the S2000) than a MB/BMW (as raced in the DTM).