In this paper, the mathematical model is developed to balance the mixed production line in the automotive industry. In the same product family, two products of front bumper are introduced and investigated with the mixed model concept. In the mixing models, the parallel and merged productions are applied in the real production of case study. With the single line balance, the mixed-model concepts result in the better objective of cost minimization and utilization, compared to the single model concept. In summary, the proposed mathematical model is suitable for implantation.