I tried carviewer just now for a GTR2 Viper I am working on but it just puts the template (after converted tobmp, also trtied the x files from GTR24u) over a NASCAR car.....so I got rid of it.
I tried another 3d thingie too, um, can't remember the name as I threw that out too, didn't do anything.
I noticed there's some kind of reference to a 3d thing with the nvidia add on with Photoshop but can't find any toolbars or anything.