Hybrid electric vehicle technology innovation and sustainable mobility: A quantile analysis of carbon footprint

Hybrid electric vehicle technology innovation, measured through patent counts, may contribute to low-carbon transport transitions by reflecting upstream technological progress rather than direct market deployment or realized emission reductions. Existing empirical evidences have largely relied on symmetric panel approaches that overlook country-specific and distributional heterogeneity. However, this research examines the asymmetric association between Hybrid electric vehicle technology innovation input, measured by patent counts, and carbon footprint in ten leading innovator economies (China, the USA, Japan, Canada, France, South Korea, Germany, the Netherlands, the UK, and Norway) using the Quantile-on-Quantile methodology. This technique improves estimation precision, offering a broad global perspective and revealing nuanced insights tailored to each country's distinctive features. The findings indicate a significant, predominantly inverse, quantile-dependent association between hybrid electric vehicle technology innovation input, measured by patent counts, and carbon footprint across most quantiles of the two variables. The impact is particularly pronounced at higher levels of both emissions and innovation. While most of the sample economies show consistently negative relationships between the variables across the distribution, Canada and Norway exhibit mixed quantile-dependent effects. These findings highlight substantial cross-country heterogeneity and underscore the importance of quantile-sensitive policy design to advance sustainable mobility and achieve climate-related Sustainable Development Goals.