To increasing fuel efficiency, every car maker research and develop parts more lightlyt. For weight reduction of part, we need not only thinner wall design, but also development of high modulus plastic material. This study is about design and material optimization, to apply low density polypropylene filled long glass fiber and rubber for IP structure. We developed 2.8kg IP structure with 20wt% long glass fiber filled high impact and modulus polypropylene and thin wall designed of 1.8~2.5mm.