The primary purpose of the Economic Effectiveness Model is to serve as a research and design tool for assessing the various implications of a mandatory program of vehicle inspection/maintenance. The model is designed to both analyze the regional feasibility of vehicle inspection/maintenance as well as to specify an optimal system design. Input data for several regional areas covering the gamut of auto related air quality problems are incorporated into the model. The model can also be used to analyze the sensitivity of system performance to various model assumptions and basic data inputs. The model is best used for evaluating the attractiveness of alternative policies, e.g., engine inspection or emission inspection, which govern and control the operation of an inspection/maintenance system. The main function of the model is in simulating the behavior of the inspection/maintenance process over time.