A compact vehicle production line is disclosed. The production line comprises a floor process of assembling floor constituent parts. Each is an aluminum alloy extrusion die cast product, which has been made, in an extrusion die casting process, by forcing molten aluminum alloy through a mold cavity in a predetermined direction. The assembled floor constituent parts are welded to make a floor structure. In an interior parts mount process, interior parts are to the floor structure to make a floor unit. In a body main process, each of two body side structures are trimmed to make a body side unit. A roof structure is trimmed to make a roof unit. The floor unit, the body side units, and the roof unit are assembled. The assembly is welded to make a body unit. In a running parts mount process, an under running unit is mounted to the body unit. In an exterior parts attachment process, color body panels are attached to the body unit.