Camaro GT3 is an official and free contend, but it's not compatible with others DLCs GT3 cars. Why not make the GT3 Camaro compatible with others GT3?
As @lordpantsington stated, the cars, the tires, the rules were very very different. Add to that, S397 has stated repeatedly they will not update much of the older ISI content. So, yeah, it's different & it will stay that way.
