The automobile industry currently faces many challenges which may greatly impact on its foundry operations. One of these challenges, consumers'' demand for greater fuel efficiency, can be met by reducing the weight of castings used in automobiles, and minimizing engineering tolerances. In answer to this particular demand, engine foundries have begun to either produce cylinder blocks or other castings with aluminum rather than cast iron. However, if a reduction in weight (thin wall and near-net shaping) can be realized with cast iron, there would be numerous merits from the perspective of cost and compactness and there would be much more flexibility in automotive parts design.In view of this, we created a new cast iron foundry production line which incorporates the following various technologies: 1) preventing mold deformation by using synthetic ceramic sand having a low coefficient of thermal expansion, 2) increasing the dimensional accuracy of molds using an air-flow and squeeze molding process and a cold box core making process, and 3) establishing foundry technology such as pouring conditions and a gating system necessary for thin wall molding. These technologies enabled us to successfully mass produce a thin wall, lightweight cylinder block having a wall thickness of 3 mm with a dimensional dispersion of °±0.6 mm (ISZ engine, employed in the Toyota''s Vitz and Yaris).Making the walls thin has enabled the weight to be reduced by approximately 5% compared with the past. Furthermore, including the effect from a near-net shape, a total weight reduction of just above 10% was able to be realized.