The SCGT stock cars are, by default, set to run in the "NAS" class. So you
have 2 options: 1 you can open each of the veh files with a text editor and
change the second line from "//DescClass=NAS" to "//DescClass=GTQ" or
whatever class you want them in. 2. You can download an additional
executable from
http://www.simracing.com/downloads/sportscar/patches_3rdparty.shtml. You
want the one listed as "24 Car (Mini, Super7, ALMS)". Only download the
BanScene version if you applied the BanScene.mas patch. Running this
executable will then show all the NASCAR stcok cars.
HTH