The American Council for an Energy-Efficient Economy (ACEEE) is calling on the EPA to consider EV efficiency in its upcoming GHG standards for cars. In an analysis posted on the organization’s website, the ACEEE shows that a small increase in EV efficiency in a future with all light-duty vehicles electrified would save 970,000 gigawatt-hours of electricity—equivalent to the electricity consumption of 21 million US homes.

With a full transition to EVs, at today’s average EV efficiency of 3.4 miles per kilowatt (mi/kWh) hour, the 300 million cars expected to be on the road in 2050 would add 1.2 million gigawatt-hours of electricity annually—a 31% increase from current electricity consumption.

However, if average efficiency was upped to the highest efficiency achieved today of 4.2 mi/kWh, full electrification of the country’s light-duty vehicles would add 970,000 gigawatt-hours—230,000 gigawatt-hours less.

Efficiency versus weight in model year 2023 EVs. Model year 2023 EVs have significantly varying efficiencies, ranging from 1.9 to 4.2 mi/kWh. Source: ACEEE.

Focusing on efficiency would also have an impact on emissions, ACEEE notes. As an example, ACEEE cites the Volvo XC40 Recharge, an SUV weighing 5,000 pounds and achieving an efficiency of only 2.5 mi/kWh. At that efficiency, it contributes about 154 grams of CO₂ per mile driven, based on nationwide grid emissions average and the latest year of data available, 2021. Over the vehicle’s lifetime, the XC40 Recharge could cause as much as 27.2 metric tons of CO₂ emissions.

Although below the average emissions of all new vehicles sold today (347 grams of CO₂ per mile), the XC40 Recharge nonetheless underperforms most EVs, notes ACEEE. Increasing its efficiency to 3 mi/kWh, which many vehicles of the same weight reach today, would reduce its emissions to 129 grams per mile and reduce lifetime emissions to 22.7 metric tons, keeping 4.5 metric tons of CO₂ out of the atmosphere.