Significantly decarbonizing road transport by 2050, in line with Paris Agreement objectives and the current research from the Intergovernmental Panel on Climate Change, will require (a) identifying and supporting the technology pathways capable of delivering deep greenhouse gas (GHG) emissions reductions on a life-cycle basis and (b) understanding the related policy challenge of time. The ICCT, ZEVTC Secretariat, has conducted a comprehensive life-cycle assessment of GHG emissions from a variety of alternative passenger car powertrains and fuels, and this briefing presents an overview of the findings and the implications for policy.