This study aims to develop the process of manufacturing car spoiler products using continuous rattan fiber composite materials. Rattan fiber was chosen because of its good strength, abundant availability in Indonesia and inexpensive price. The study was conducted by testing the strength of a composite rattan fiber, simulation using computer software, comparing with pre-existing spoilers and making prototypes of spoilers. Based on the results of the study, the strength of continuous rattan fiber composite materials with polymer matrix is as follows: maximum tensile strength of 27 MPa, maximum compressive strength of 44 MPa, maximum flexural strength of 46 MPa, and maximum impact strength of 29 kJ/m 2 . As a comparison, ABS plastic material used in many car spoilers has a maximum tensile strength of 35 MPa, a maximum compressive strength of 48 MPa, a maximum flexural strength of 56 MPa, and a maximum impact strength of 31 kJ/m 2 . From the results of the simulation of loading using software carried out on the composite material of polymer rattan fibers, we obtain a compressive strength of 2000 N load of 51 MPa with compressive strain of 0.00873 mm/mm. From the results of simulation loading using software carried out on ABS plastic material, we obtain a compressive strength for the 20110 N load of 48 MPa. The manufacturing process has produced a prototype of spoilers that are ready to use with good results. The results of this study will be a reference for the next development.