[Abstract] The paper deals with the optimal design of road vehicles and their subsystems. The highly competitive nature of the automotive industry demands constant product innovation and reduction in product development both in time and cost while satisfying performance and legal requirements. Optimization procedures provide a scientific approach to automatically determine the most efficient designs under the target operating environment. Particular attention is devoted to the class of methods pertaining to complex system design optimization, as well as the approaches for the optimal design of complex systems under uncertainty. A critical review of the optimization methods used for solving road vehicle system design problems is reported. Some examples of design optimization are given in the field of vehicle system dynamics, powertrain design, internal combustion engine design, active and passive safety, vehicle system design and lightweight structures, advanced automotive electronics.