I've made such a thread for GT1 and decided to do one for GT2. Here are some piccies I found so far, feel free to add others if you find them:
Ford (1997 Ka Brochure)
View attachment 1219000
Chevrolet (1997 Z28 Brochure)
View attachment 158079
Vector Automotive (M12 brochure, forgot which year)
View attachment 158080
BMW (1999 3-Series brochure)
View attachment 158081
Honda (NTSC-J, 1997 Japanese Brochure)
View attachment 158082
FIAT (1999 Barchetta brochure)
View attachment 1219002
Shelby
View attachment 158084
Subaru (1999 Impreza Version VI brochure)
View attachment 158085
Audi (I found only one of the pictures, 1998 TT brochure)
View attachment 158086
Jaguar (XKR 1998/99 brochure)
View attachment 1219008
TVR (1998/99 brochure)
View attachment 1219009
Plymouth (unknown)
View attachment 1219010
MGF (1998 brochure presumably)
View attachment 158099
Opel (can't find it in a bigger resolution, 1998 brochure)
View attachment 158246
Mazda (1999 RX7 Factory ad)
View attachment 169937