This paper presents a multi-period optimization model for strategic fleet electrification under conditions of fuel price volatility, time-limited subsidies, and vehicle performance degradation. The model is formulated as a mixed-integer linear program that allows decision-makers to determine the optimal timing and scale of electric vehicle acquisitions, balancing operational cost, environmental penalties, and investment constraints. Rather than assuming static inputs or single-period trade-offs, the formulation captures how evolving economic and policy signals shape long-term replacement strategies. Key features include scenario-based pricing, degradation-adjusted fleet capacity, and flexible treatment of emission costs.
The model is designed to support both theoretical exploration and applied decision-making. It can be used with synthetic inputs to evaluate transition behavior under different assumptions. A numerical illustration demonstrates how policy design, cost trajectories, and degradation rates interact to determine investment timing. The framework is extendable to incorporate stochastic vehicle lifetimes, uncertain demand, and mixed-technology fleets. By structuring these interdependencies explicitly, the model offers a planning tool that is transparent, adaptable, and grounded in the real trade-offs facing fleet operators today.