http://nasanorcal.com/25hr/2015/Teamvehicles.htm
Here is an updated entry list. Some more interesting entries including a Praga R1 (if I'm not mistaken are raced in the Dutch Supercar Challenge)
Factory Five entering their GTM kit car, oddly TFB's BMW car was listed and now is off, yet their site says they are competing in the 25...might be a couple more entries at the last minute