In recent years plastics have been finding increasing application in underhood performance parts due to good thermal performance, weight reduction, cost savings, and design flexibility. Downsized cars with lower hood lines and smaller engine compartments as well as an increasing dependence on sophisticated electronics have placed stringent demands on the performance of plastic components. Automotive materials have an increasing demand for higher heat, humidity, and chemical resistance.Polymethylpentene (PMP) is a semicrystalline “engineering polyolefin” which melts at 240°C. It has a density of 0.835 g/cc, one of the lowest of all polymer resins. PMP also exhibits high optical clarity, good thermal and chemical resistance, outstanding electrical properties, and good processability. Mechanical properties at room and elevated temperatures are improved by the addition of glass reinforcement. The resultant compounds have excellent electrical properties, high strength, and good thermal and chemical resistance, which are beneficial in a variety of automotive applications.The preliminary properties of several glass reinforced compounds of PMP are presented in this paper. These properties are compared with those of several engineering plastics presently being used in the automotive industry.