Feds’ Overhaul of Efficiency Ratings Could Affect More Than Just EVs

The Energy Department announced new rules that would recalculate MPGe scores and how they apply to fleet averages for automakers.

byAaron Cole|
Electric Vehicles photo

Federal regulators want to change how electric vehicles’ fuel economy is calculated going forward, reducing the impact that EVs can have on overall fleet averages and forcing automakers to improve efficiency. The Energy Department on Monday proposed rules that would slash efficiency for electric vehicles, in some cases by more than two-thirds.

Under new rules, the Volkswagen ID.4 electric car’s Miles Per Gallon-equivalent (MPGe) rating would fall from 380.6 to 107.4. The Ford F-150 Lightning’s MPGe rating would drop from 237.1 to 67.1 MPGe. The proposed changes come ahead of sweeping reforms to emissions targets that will be unveiled Wednesday.

Environmental groups such as the Sierra Club support the move, while the Alliance for Automotive Innovation, a lobbying firm representing most major automakers, said recalculating the mileage would discourage EV adoption. 

The recalculation would have little impact on the range of most new EVs on sale. Rather, it would impact the effect selling those cars would have on the overall fleet average for those automakers, also called Corporate Average Fuel Economy (CAFE). By recalculating the MPGe for EVs sold, the net impact could be a lower CAFE figure for automakers and force them to sell vastly more efficient models powered by either internal combustion or sell EVs in greater quantities. Automakers routinely miss CAFE targets, although they can buy and sell CAFE credits to each other for undisclosed prices, usually tens of millions of dollars. Reuters reported that in 2016 and 2017, Stellantis (then Fiat Chrysler) paid $152.3 million in CAFE penalties. 

The calculated MPGe score is determined by using fixed numbers for electricity, the energy density of petroleum, and driving patterns that haven’t been updated in more than 20 years. The score aims to approximate how efficient EVs are with the electrical equivalent of one gallon of gasoline, calculated at about 33.7 kWh for one gallon of gas. A high MPGe score doesn’t necessarily constitute a longer range, just better efficiency. 

Automakers have long said that increasing safety requirements and mandating better fuel economy has made cars more expensive, although recent data suggest that may not be true.

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