An Empirical Assessment of Greenhouse Gas Emissions and Environmental Performance of Hybrid Vehicles in the European Union

This study provides an empirical assessment of greenhouse gas emissions and the environmental performance of hybrid vehicles in the European Union. The analysis integrates a macro-level examination of nitrous oxide (N 2 O) emission trends in EU Member States for road and pipeline transport with a micro-level econometric investigation of emissions generated by the internal combustion engines of hybrid vehicles. The empirical analysis is based on a large sample of hybrid vehicles of different brands and variants, including 1350 observations used to examine the relationship between CO 2 emissions and fuel consumption per 100 km, and 123 observations to analyze nitrogen oxides (NO x ) emissions. CO 2 is assessed as the principal greenhouse gas emitted during vehicle operation, while NO x (NO and NO 2 ) is examined as a major regulated atmospheric pollutant relevant to environmental performance. A bibliometric analysis of NO x -related publications further highlights increasing scientific attention to this pollutant, supporting the relevance of the current study. Results reveal significant heterogeneity across hybrid vehicle models in terms of fuel consumption and NO x emissions, indicating that environmental performance is strongly influenced by technological design and operational characteristics. Robust multiple regression models (R 2 = 0.84 for vehicle with low CO 2 emissions, 0.82 for high CO 2 emissions and R 2 = 0.72 for NO x emissions) revealed significant correlations between pollutant emissions and fuel consumption, providing valuable tools for predicting emissions and informing environmental policies and hybrid vehicle design. Overall, the findings indicate that hybrid vehicles can contribute to improved environmental performance and lower greenhouse gas emissions relative to conventional vehicles, while their effectiveness depends on model specific characteristics and broader sectoral emission dynamics in the EU. These insights provide evidence for policymakers and industry stakeholders to support the transition toward cleaner vehicle technologies and align climate neutrality targets in the European Union.