Formal design optimization involves application of mathematical optimization techniques to models derived from engineering science, often presented as computer simulations. Industry use of design optimization tools is now widespread and sophisticated. As the size and complexity of design problems addressed with these formal methods increase, so do the challenges for successful implementations. Based on the author's experiences, after briefly reviewing the mathematical challenges involved, the article describes several problem areas where optimization technology is likely to have a major impact in the development of improved artifacts in the coming years. These include conceptual and topological design, large complex systems, smart products, and enterprise-wide product design.