Although electric vehicles (EVs) do not have tailpipe emissions, they consume electricity which produces carbon dioxide (CO2) at the point of power generation. Electricity consumption is measured under the standardised test cycles. An emission factor is applied to the electricity consumption to compute the CO2 of the EV. As the electricity consumption of EVs accounts for negligible amounts of emissions of the four new pollutants at power generation, EVs are thus assumed to emit no hydrocarbons (HC), carbon oxide (CO), nitrogen oxides (NOx) or particular matter (PM).
The emission factor applied is based on the Grid Emission Factor published by the Energy Market Authority (EMA), which is the amount of CO2 emissions produced for every unit of electricity generated from the burning of fossil fuels at the power stations in Singapore. The historical values of GEF can be found at .