With a 212.7-kWh battery pack that tips the scales at 2,923 pounds (1,325 kilograms) and a curb weight of 9,063 pounds (4,111 kilograms, the GMC Hummer EV is not your average planet-saving electric vehicle.

We already knew that the all-electric pickup truck's efficiency is not something to brag about ever since we learned about it EPA rating of 47 MPGe on the combined cycle. But a new study sheds light on an aspect that's often overlooked: the CO2 emissions of EVs deriving from the way the electricity that powers them is produced.

While EVs have zero tailpipe emissions, they are still responsible for greenhouse gas emissions, according to a study by the American Council for an Energy-Efficient Economy (ACEEE), a non-profit research organization focused on reducing energy waste and combat climate change.

The organization argues that policymakers and advocates should explore ways to increase EVs' efficiency and reduce their environmental impact, as about 60 percent of electricity in the United States is generated by burning fossil fuels. ACEEE notes that until the grid is completely carbon-free, there will be emissions from generating the electricity to run EVs, known as upstream emissions.

The non-profit uses the Hummer EV as an example in this respect, calculating that the electric pickup emits 341 grams of CO2 per mile when accounting for emissions from the electric grid. That's significantly higher than the Bolt EV's 92 grams of CO2 per mile and exceeds even the gas-powered Chevrolet Malibu's rating of 320 grams per mile.

Gallery: 2022 GMC Hummer EV First Drive

Still, compared to the original Hummer H1's rating of 889 grams of CO2 per mile and other similar gas-powered trucks that are on sale now, the electric GMC Hummer is way more environmentally friendly.

ACEEE points out that the environmental impact of EVs isn't just about the electricity generated to power each mile, with the manufacturing process also causing the release of greenhouse gases at several stages, known as the embodied emissions of the vehicle.

EVs use minerals that need to be mined, processed and turned into batteries, and as automakers pursue ever greater driving ranges, the batteries often grow larger, with embodied emissions increasing in the process. Of course, the same could be said about efforts to extract and refine petroleum that add to ICE-powered cars' tailpipe emissions.

The organization argues that policymakers and automakers need to focus more on the efficiency of electric vehicles as they proliferate.

"The Environmental Protection Agency should explore ways to factor EV efficiency into fuel-efficiency and greenhouse gas standards, starting with accounting for EVs' upstream emissions. At the moment, regulators calculate the emissions from gasoline vehicles and set requirements for automakers, but EVs are counted as causing no CO2 emissions."

ACEEE believes that accounting for upstream emissions would mean that "the sale of a more efficient EV would be more advantageous for automakers to meet their regulatory requirements." Check the link below for the full study.

Got a tip for us? Email: tips@insideevs.com