I only use sweethome3D no other program

on 3dwarehouse Download the model as Collada file
make a new directory on your pc ( 2010 GMC Sierra 3500 HD ) extract everything , its making a directory model with all the textures and in the root u see model.dae , import that file ( model.dae ) directly in SH3D

also made a 2x8+by+8+foot+stud+wall+door with a door opening

sentver10brickmancave32x42-2 with your car