The focus of this paper is on the design of the engineered system comprising various subsystems that have functional interactions amongst themselves. Depending on the system architecture, subsystems can be classified into one of the two types: scalar and modular subsystems. Each subsystem is defined by various primary and secondary parameters, performance criteria, and compatibility constraints. The objective function is formulated as minimization of total cost of all the subsystems while meeting the required performance criteria. The cost of an individual subsystem is a function of parameters of that particular subsystem. The complete engineered system level problem has been formulated as a non linear programming optimization problem. The application of the proposed methodology is demonstrated using an example of the automotive truck family.