Clarifying the “gains” and “losses” of transport climate mitigation in China from technology and efficiency perspectives

China’s transportation industry, with its typical characteristics of “high energy consumption and high emissions”, is a key point for China’s CO2 emission reduction. An investigation of the driving factors of China’s transport energy-related CO2 emissions has great importance for clarifying the “gains” and “losses” as well as the future focuses of CO2 emissions emission reduction in this sector. Existing studies on the driving factors of transport CO2 emissions in China fail to incorporate effects of technology and efficiency into decomposition analysis framework. Based on the provincial panel data of China’s transportation industry for the period of 2004–2016, this paper uses a comprehensive decomposition framework, which combines the logarithmic mean Divisia index method (LMDI) and production-theoretical decomposition analysis (PDA), to decompose China’s transport CO2 emissions into nine components: emission factor effect, energy structure effect, scale effect, regional structure effect, energy-saving technology effect, production technology effect, energy efficiency effect, production efficiency effect, and potential energy intensity effect. The main results indicate that: (1) during the sample period, China’s transport industry witnessed 498.998 million tons (Mt) CO2 emissions growth. Scale effect was the largest contributor, followed by production technology, energy-saving technology, and energy structure; (2) the improvement of energy efficiency and production efficiency, the decline of electricity’s emission factor, and regional structure adjustment played active roles in the CO2 emission reduction of transportation industry; (3) the performance of various driving factors varies greatly in different provinces. Local governments should establish and implement policies tailored to their characteristics.