If you mean the second car of one/your team is not the same as the first
then simply copy car_yourcar_ca1_lod_0.gp4 and paste to another folder,
rename as car_yourcar_car2_lod_0,gp4 and paste back into wad overwriting whats already there.
Now car 1 and 2 should be your car. Also if the other
lod's are the same as the old williams e.g lod 1,2,3 and 4 then you'll need
to copy lod_0 eight times four for each car renaming to each lod
respectively and pasting back to wad.
Hope that's what your after:D
Richard.