The U.S. transportation sector consumes over one third of the nation’s energy and accounts for 27% of its greenhouse gas (GHG) emissions. Vehicle manufacturers use electrification and mass reduction to decrease vehicle use phase energy and GHG emissions. But, life cycle assessment (LCA) is required to fully understand these impacts due to electricity and lightweight material production burdens. This work develops a framework to simultaneously evaluate electrification and lightweighting to help guide vehicle design. This framework is applied to assess the life cycle energy and GHG emissions of a conventional vehicle (CV), hybrid electric vehicle (HEV), and plug-in hybrid electric vehicle (PHEV) constructed of baseline or lightweight materials. Baseline vehicles are designed according to powertrain configuration; powertrain mass has a significant influence on vehicle mass and powertrain design determines the functional needs from related subsystems (e.g. regenerative braking). Simulation results highlight the importance of simultaneously considering vehicle electrification and lightweighting because the impact of mass reduction on fuel economy is unique to each powertrain.