Product design is inherently a key component of brand strategy. Accordingly, significant resources are invested to improve product and brand performance; however, foundations for understanding the role product design plays in influencing actual consumer opinions from the marketplace have not been fully explored in the literature. This paper develops a conceptual framework illustrating how two critical design factors—form and function—impact consumer opinion and delineate brand-specific effects. Nonmonotonic effects are identified, as well as the interaction effects of the individual factors among the dimensions. A longitudinal model based on objective measures of form and function is tested with a data set developed from models available in the U.S. automotive market from 1999–2007; it includes 16 firms, 32 brands, and 137 products. The results indicate the relationships between factors of form and function are multifarious and complex, but clearly play a significant role in forming consumer opinions, although they do exhibit diminishing returns. The findings further indicate brand-specific effects exist, and consumer opinions vary by brand. The findings provide foundations for understanding the interplay between product development and brand management. Overall, this research supports the notion that brand strategies can be supported through the management of design dimensions.