Battery Electric Vehicles (BEV) have been promoted and required by many governments towards the need to reduce transportations CO2 emissions. BEV are not “Zero Emissions Vehicles” because they run on grid electricity, but could be ‘effectively ZEV’ if the incremental CO2 is ‘very small’. To answer this question at the national level, three metrics are needed and estimated: (1) ICEV fuel consumption, approximated by the total US gasoline consumption divided by the total fleet miles driven, 25 mpg or 350 g CO2/mi. For strong HEV it is about one third less, 240 g CO2/mi. (2) BEV energy consumption, using data from systematic on-road testing of a wide range of vehicles, estimated at 40 kWh/100 mi for a US sales mix. (3) Electric grid marginal CO2, with ranked order sourcing: zero-CO2 sources are prioritized and supplemented by fossil sources. IEA hourly data show that the US 48 contiguous states are nearly self-contained, with zero-CO2 sources providing about a third of total demand. The response to fluctuating demand comes largely from natural gas and coal power stations, with EPA data showing a marginal CO2 of 600 g CO2/kWh. For a driver switching from an ICEV to a BEV, the reduction in gasoline use, - 350 g CO2/mi, is offset to two thirds by an increase from higher electricity consumption, 40 x 600 / 100 = + 240 g CO2/mi. The BEV incremental CO2 is similar to that of the strong HEV, and not ‘much smaller’ than the ICEV. This is not a coincidence, as HEV engines operate at about 40% efficiency, substantially the same as the fossil grid, but directly inside the vehicle.