UV stability is an extremely important design property of colored performance plastics for the automotive industry. Moreover, US automakers have been demanding improvements in polymer UV stability over the last several years. This has culminated in the development of test method SAE J1885, which uses a Xenon arc weather-ometer to test the UV stability of interior trim components. This more stringent test method required all suppliers to re-evaluate their position in this market and most likely develop new grades to meet the requirements of this J1885.Acetal is one such polymer which Hoechst Celanese embarked upon a major product development effort to meet the demanding requirements of J1885 for molded-in-color. This development work focused on the total stabilizer/additive system, whereby each component was assumed to be either beneficial or detrimental to UV stability. Results of this work emphasized the importance of reducing a total system approach to practice, as an improved UV stabilized grade of acetal copolymer was developed. This paper focuses on the conclusion of this product development effort.