A country-based well-to-wheel efficiency comparison of electric and fossil-fuelled vehicles: A comprehensive study considering fuel sources and policy implications

Increasing energy demand brings environmental challenges, especially due to the dependence on fossil fuels. Despite importance of energy supply, they cause damage to the environment. For sustainability, the transition to alternative energy sources is accelerating. The transport sector that is heavily dependent on fossil fuels consumes a large portion of energy. Efficient engines, lightweight materials and alternative fuels are required to reduce emissions. Promoting advanced vehicle technologies and clean fuels helps to reduce urban pollution. While electric vehicles are key to this transition, their environmental benefits are highly dependent on a country's electricity mix. A comprehensive assessment of energy and emissions is essential. This study conducts a comprehensive Wheel-to-Wheel analysis to assess the energy efficiency of EVs compared to diesel and petrol vehicles in eight countries with different electricity generation profiles, encompassing both the upstream well-to-tank fuel cycle processes and the downstream tank-to-wheel conversion stages within the full energy pathway. The analysis shows that diesels exhibit the highest average WTW efficiency among internal combustion engines at 25.37 %, while petrol vehicles lag behind at 18.20 %. However, EV-WTW efficiency ranges widely, from 36.54 % in the Netherlands, where renewable energy dominates, to only 21.26 % in Saudi Arabia that is heavily dependent on fossil fuels. The real world energy consumption of EVs also varies significantly. The findings emphasize that although EVs are a promising solution for sustainable mobility, their actual environmental performance is conditional. Countries should prioritize grid decarbonization to realize the full potential of EVs. The novelty of this study lies in integrating real-world vehicle data with country-specific WTW modelling, providing a critical lens for policymakers to align transport electrification with clean energy transitions.