Hey! If you mean the exact GT PSP versions, there's a format trap: GTPS2ModelTool dumps GT3/GT4 car files (CAR4/MDLS), but GT PSP uses MDL3, so that tool won't export these PSP cars.
Jpcsp can export the current 3D scene to OBJ/MTL with PNG textures (File > Export 3D scene; look in its export/Export-* folder). That's a scene capture, though, not a finished car: in Blender you'll need to remove the surrounding geometry and duplicate reflection meshes, and fix some glass/decals. This older GTPlanet walkthrough shows the GT PSP cleanup. Once it's clean, Blender can export FBX.
If GT4 versions of the RX-7 LM and Raybrig NSX are acceptable, GTPS2ModelTool can dump the body to OBJ from a GT4 car file, though wheels may still need separate work. Are you after the exact PSP meshes? If you've tried Jpcsp already, what part of its OBJ is missing or broken?
Mate, made these for you. Both cars are in the ZIP as OBJ and FBX, with wheels and textures. They're the GT4 models, not the exact PSP meshes. Couldn't resist making you a render as well.
