Navigating sustainable mobility: Wavelet insights into carbon emissions in Germany's transportation sector

Achieving carbon neutrality by 2045 is a key national goal in Germany, where the transportation sector—currently responsible for 20 % of the nation's total CO2 emissions—remains one of the most challenging areas for decarbonization. This study investigates the influence of biofuels (BIOF), energy productivity (ENGP), infrastructure development (INFD), and sustainable energy innovation (SEIN) on transport-sector CO2 emissions (TCO2) in Germany. Using quarterly data from 2000 to 2021, a wavelet-based analysis is employed to examine the dynamic relationships between these structural variables and emissions across multiple time horizons. The findings reveal that BIOF, ENGP, and SEIN are negatively associated with transport emissions, while INFD is positively correlated. Notably, BIOF and SEIN exhibit stronger mitigation effects in the medium and long term, whereas INFD contributes to emission increases across both short- and long-term scales—underscoring the importance of aligning infrastructure planning with climate objectives. The outcomes are robust and further validated through wavelet-based OLS regression. This paper provides novel empirical evidence based on high-frequency transport data and offers actionable policy recommendations that support Germany's Climate Action Law and EU-level climate frameworks. The insights also hold relevance for other countries seeking to design sustainable mobility pathways modeled on advanced economies like Germany.