A motor vehicle sub-frame is provided. That motor vehicle sub-frame includes a front cross member, a rear cross member and first and second side rails connected to the front and rear cross members at each side of the sub-frame. The side rails both include a first component having a first extrusion axis and a second component having a second extrusion axis. The first and second components are joined together so that the two components effectively form an at least partially closed or boxed construction providing enhanced bending and torsion resistances while minimizing component weight.