The automotive industry is facing significant challenges for next-generation vehicle design as fuel economy regulations and tailpipe emission standards continue to strive for greater efficiency. In order to ensure vehicle design reaches these sustainability targets, lightweighting through multi-material design and topology optimization (TO) has been suggested as the leading method to reduce weight from conventional component and small assembly structures. More effective tools, techniques, and methodologies are now required to advance the development of multi-phase optimization tools beyond current commercial capability, and help automotive designers achieve critical efficiency improvements without sacrificing performance. Presented here is a unique tool description and practical application of multi-material topology optimization (MMTO), a direct extension of the classical single-material problem statement (SMTO). In this implementation the TO problem is expanded to include material existence and selection design variables in the typical density method while utilizing the solid isotropic material with penalization (SIMP) interpolation scheme. Further improvements from prior research include adoption of the method of moving asymptotes (MMA) with barrier methods for handling large-scale, high-resolution optimization problems. Emphasized in this paper is a description of a multi-material topology optimization computational tool, an examination of single and multi-material solutions and comments for practical design. First, key equations and techniques that enable MMTO are presented, including interpolation schemes, sensitivity analysis, and filtering methods. Next, MMTO is applied to a practical automotive case study in a minimum compliance framework, and compared to other SMTO approaches. Lastly, an overview of practical design considerations is presented to discuss development of a final product from concept to validation.