Both product line engineering (PLE) and model driven architecture (MDA) are emerging as effective paradigms for building a family of applications in cost effective way. PLE supports this by reusing common assets and MDA supports this by generating applications on diverse platforms through model transformation. However, both technologies have shortcomings to be a comprehensive methodology. The instructions and artifacts of PLE processes are not yet precisely defined. Especially, instructions for detailed design considering implementation platforms are not yet provided. Careful observations on PLE and MDA reveal that they complement each other by overcoming their limitations. We find a possibility of seamless integration, resulting in a comprehensive commercial-level methodology. In this paper, we propose a practical product line methodology, DREAM, which adopts key activities of PLE and model transformation feature of MDA. By applying the proposed methodology, it becomes possible to efficiently and semi-automatically develop a large number of applications that vary on behavior and implementation platform.