The composite rocker cover is one of the most popular global automotive applications for thermoplastics under the hood. Used as part of weight and cost reduction programs, thermoplastic rocker covers have been replacing metal parts for more than 10 years, and growth is expected to continue into other power-train applications.As the automotive industry continues to seek greater cost reductions, the integration of the thermoplastic rocker cover with other components is becoming a viable option. For example, in a recent rocker development for the Hyundai Atoz, it was discovered that there was no cost advantage in simply replacing the inexpensive pressed steel component with nylon. Although the company would benefit from the weight savings traditionally associated with the conversion from steel to thermoplastic, there was no cost driver. In order to meet target cost reductions, the rocker arm cover was integrated with the air cleaner into a single injection molded part. This provided significant cost savings and is expected to spur similar parts consolidation efforts and accelerate the growth of engineering plastics in under hood applications.This paper will review the integrated concept and design, and provide information on the use of predictive acoustic analysis and warpage analysis to design the part and tool structure.