Abstract
Passenger vehicles are responsible for significant greenhouse gas (GHG) emissions, which calls for accurate and up-to-date estimates of the comparative emissions of the main types of alternative power trains, to enable evidence-based policy recommendations. This paper provides a systematic review and harmonization of the recent scientific literature on this topic. The results show that battery electric vehicles (BEVs) represent the most promising option to decarbonize the passenger vehicle fleet in all considered world regions, with up to −70% reductions in GHG emissions possible, vs. conventional internal combustion engine vehicles (ICEVs) running on petrol. Hybrid electric vehicles (HEVs and PHEVs) are less effective strategies, but they may be useful in bridging the gap between ICEVs and BEVs, especially in those markets that are harder to electrify quickly. Finally, fuel cell vehicles (FCEVs) may also be a viable option, but only if the hydrogen fuel is produced via water electrolysis using renewable energy.