Book excerpt: With their high specific strength and stiffness, composites have the potential to significantly lower the vehicle weight, which can have a dramatic effect on improving fuel efficiency and reducing greenhouse gas emissions. For the past decade or so, composites have been experiencing several transitions, including the transition from micro-scale reinforcement fillers to nano-scale reinforcement fillers, resulting in the nanocomposite. The effectiveness of the nano-sized fillers in composites can be explained by one of their unique geometric properties: the length-to-thickness aspect ratio. Therefore, nano-sized fillers have exceptionally higher reinforcing efficiency than the conventional, large fillers. The effectiveness of the nano-sized fillers in composites is also due to their large surface area and surface energy. This book consists of a collection of technical papers selected from the automotive composites and other relevant sessions that the editors have organized for the SAE World Congress over the past decade. It begins with a section on the perspectives of nanocomposites in the automotive industry, with of three excellent papers given by experts from the industry and academia. Following, it brings to the reader in-depth information on the three major nanocomposites categories: o Nano-fiber reinforced composites o Nano-platelet reinforced composites o Nano-particle reinforced composites