Reliability growth method is as a supporting tool for the production readiness plan of a new product line, in order to have an estimated probability of field failures during normal production. This is accomplished in the case study presented herein using prototypes test bench data. Evaluation is carried to verify its adequacy to support new product launch. Additionally, continuous improvement and evaluation of design change impact on product performance is another potential application of the method. In the case study a reliability growth planning and assessment is conducted prior to a new alternator pulley product line launch to confirm initial durability targets of the product could be achieved during transition from R&D validated prototype to the mass production items of the new product line. It includes efforts from Product Engineering during development stages until Start Of Production (SOP). Planned reliability growth curves are compared to the assessment ones based on durability tests, which include data from concept validation prototypes up to production-intent design samples. Failure mode analysis is an inherent part of this method, helping on the definition of corrective actions to adjust initial concept design to the specific characteristics of each new application. Results shown in the present work clearly demonstrates reliability growth method could be applied as an effective way to control and report performance evolution of new product lines, preventing early failures. Results highlight the evaluation carried with the method proposed during advanced product quality plan to improve product reliability based on preliminary bench test data.