Dynamic models are routinely used in the development of sustainable transportation systems. Yet, policymakers question the reliability of the estimates they produce. More holistic models that include a dynamic well-to-wheel system perspective, built-in sensitivity tests, and ask ‘what if’ policy questions can potentially improve the robustness of the estimates. Accordingly, we develop a system dynamics, fleet-based, life cycle model that offers these features and apply it to Brazil’s electric-vs-ethanol debate. We present the results through different scenarios, from business-as-usual to more extreme dependence on particular energy sources. Amongst other things, they show that ethanol dominates in most scenarios except under certain long term land use assumptions that heighten well-to-tank emissions. They also highlight the sensitivity of LCA results to underlying assumptions and encourage the standardisation of reporting norms. Finally, our model highlight where ambiguities are likely to materialise, providing useful insights to practitioners in Brazil and elsewhere.

动态模型通常用于可持续交通系统的开发。然而，政策制定者质疑他们做出的估计的可靠性。更全面的模型，包括动态油井到车轮系统的观点、内置的敏感性测试，并提出“假设”政策问题，可能会提高估计的稳健性。因此，我们开发了一个系统动力学、基于车队的生命周期模型来提供这些功能，并将其应用于巴西的电动与乙醇辩论。我们通过不同的场景展示结果，从一切照旧到对特定能源的更极端依赖。除其他外，他们表明乙醇在大多数情景中占主导地位，除非在某些长期土地使用假设下会增加油井到油箱的排放。他们还强调 LCA 结果对基本假设的敏感性，并鼓励报告规范的标准化。最后，我们的模型突出了可能出现歧义的地方，为巴西和其他地方的从业者提供了有用的见解。