Within the next 5 to 10 years optical fibers are expected to be used in automobile local area networks. For this application, both glass and plastic fibers have the potential to play a significant role. Under the hood, where the operating temperatures tend to be too high for plastic fibers, glass based fibers are likely to be used. Glass based fibers are also intended for use in fiber optic sensors, for example, in engine control systems. However, in general, the preferred fiber material is plastic due to economic considerations. In the case of optical fibers for a network within the passenger compartment, plastic optical fibers are adequate and several prototype systems have already been built and demonstrated. The principal reasons for considering the use of optical fibers are discussed in several papers (1-3). A key component in an optical fiber network is a star coupler. This paper will deal with the fabrication and test results of a prototype 7x7 transmissive star coupler developed at Battelle. The optical fiber diameter chosen for the development of the star coupler is a 1 mm diameter fiber manufactured by Mitsubishi (ESKA-40). Currently both 750 and 1000 micron diameter fibers are under consideration for the automobile but the technology reported here is capable of accommodating either fiber. The final choice of the fiber type will depend on several economic factors which are yet unknown.