In the period 1990-2007, CO2 emissions from Ireland's Transport sector increased by 181%. It has been proposed that a transition to EV (electrically-powered vehicles) - either BEV (battery-powered) or PHEV (plug-in hybrids) - offers the potential for significant reductions in these emissions. However, the benefits of PHEV - and of plug-in vehicles generally - accrue because some fraction of the fossil fuel normally consumed by the vehicle is displaced by electricity extracted from the national grid. The net benefit therefore depends on many factors, including the characteristics of the electricity generation and distribution system, and the proportion of vkm (vehicle-kilometres) completed under electric power. This paper examines these factors in an Irish context. On the basis of individual vehicles, it is found that electrification yields substantial and immediate reductions in GHG (greenhouse gas) emissions for urban-type driving cycles. For inter-city travel, however, the percentage reduction attainable is much smaller, and the technical difficulty of achieving this capability is much greater. Unless that challenge can be overcome, it is shown, 50-75% of CO2 emissions from private cars will remain beyond the reach of electrification. (C) 2010 Elsevier Ltd. All rights reserved.