Alternative passenger car fleet decarbonisation pathways in Europe

Achieving rapid reductions in real-world CO 2 emissions from road transport requires not only ambitious CO 2 standards for new vehicles, but also policy designs that accelerate fleet turnover and promote electric driving under real-world conditions. An open question is whether passenger car fleet decarbonisation can be achieved solely through full electrification or also through plug-in hybrid powertrain configurations that operate predominantly in electric mode. While the European Union's (EU) current CO 2 standards focus on type-approval performance of new vehicles, their climate impacts depend critically on fleet turnover rates, fuel mix, as well as user behaviour, particularly during the transition period up to 2040 when the displacement of internal combustion engine vehicles is most critical. This study uses a scenario-based assessment framework to examine alternative decarbonisation pathways for the EU passenger car fleet up to 2050. Two scenarios are compared: a baseline pathway consistent with the current EU CO 2 standards, and an alternative stylised pathway reflecting possible market responses to the European Commission's Automotive Package. Particular attention is given to the role of plug-in range-extended electric vehicles (PREVs), together with conventional plug-in hybrid electric vehicles (PHEVs), as complementary technologies to pure electric vehicles (PEVs) that may support faster fleet renewal under regulatory flexibility supporting technological neutrality. Results indicate that under favourable conditions, the alternative pathway leads to lower cumulative tailpipe CO 2 emissions than the baseline pathway with reductions of about 8% between 2028 and 2040. However, the results show that these benefits are highly sensitive to real-world use. If PREVs are operated with electric driving shares similar to current use of PHEVs, the gains are substantially reduced and can reverse beyond 2040 in the longer term. Differences relative to the current standards pathway remain limited up to 2040 because older internal combustion engine vehicles still dominate fleet emissions during much of the transition. The results also indicate persistent demand for liquid fuels in mixed electrification pathways, highlighting the importance for achieving decarbonisation targets of low-carbon fuel supply for road transport alongside electrification. Overall, these findings suggest that regulatory flexibility allowing technological neutrality over the next decade does not automatically accelerate or delay decarbonisation. Its effectiveness depends largely on the conditions under which it is implemented, especially real-world electric driving, fleet-turnover dynamics and supporting fuel and electricity pathways, with prudent assumptions suggesting that until 2040 decarbonisation would not be slowed.