I had this problem with my existing cars.wad. Imported the new minardi textures (changed them to prost first - i'm using the prost slot for minardi), but nothing was visible. Maybe I shouldn't have chaged them to prost?
Larry
AMD 3000+,Epox EP-8RDA,Ram 1536mb 333 DDr, Rad 9800 pro omega 2.4.96, dx9b, Audigy, MOMO FF,winxp