This paper discusses a technique for the examination of countermeasures at the early stage of vehicle development to realize efficient enhancement of the engine combustion noise quality. The key point of this technique is to utilize the existing combustion noise quality evaluation method as a simulation technology at the design stage of development. By doing this, the necessary measures can be estimated using the in-cylinder pressures of the newly developed engine measured on the bench and the structure response functions obtained from the previous mass-production vehicle. This process was applied to the new Kei car development and the results demonstrated the effectiveness of above technique.