gui you cant in gp3 im afraid.
Im guessing that ur refering to the pics on fasters website? im which case he probably put the one carshape in and took the pictures of the cars that used that carshape and then started the game with the other carshape and took pictures of the liveries that use that carshape
in the game itself you have to choose between the low back and high back (only see mindaridi with this one) carshapes (its what makes seasons with high and low nosecone shapes irritiating (96, 94 e.t.c. :P) but you get used to it