The ‘greenest’ car in America might surprise you

But a new report from the American Council for an Energy Efficient Economy suggests that the “greenest” car in America may not be fully electric. The nonprofit group, which has rated the pollution from vehicles for decades, says the winning car this year is the Toyota Prius Prime SE, a plug-in hybrid that can go 44 miles on electricity before switching to hybrid.

“It’s the shape of the body, the technology within it, and the overall weight,” said Peter Huether, senior research associate for transportation at ACEEE. “And all different types of Priuses are very efficient.”

It’s not the first time that a plug-in vehicle has topped the GreenerCars list; the Prius Prime also won out in 2020 and 2022. But with more and more electric vehicles on the market, the staying power of the plug-in hybrid is surprising.

The analysis shows that simply running on electricity is not enough to guarantee that a car is “green” — its weight, battery size and overall efficiency matter, too. While a gigantic electric truck weighing thousands of pounds might be better than a gas truck of the same size, both will be outmatched by a smaller, efficient gas vehicle. And the more huge vehicles there are on the road, the harder it will be for the United States to meet its goal of zeroing out emissions by 2050.

The GreenerCars report analyzes 1,200 cars available in 2024, assessing both the carbon dioxide emissions of the vehicle while it’s on the road and the emissions of manufacturing the car and battery. It also assesses the impact of pollutants beyond carbon dioxide, including nitrogen oxides, carbon monoxide and particulate matter — all of which can harm human health.

Combining these factors, the authors gave each car a “green score” ranging from 0 to 100. The Toyota Prius Prime received a score of 71, followed by several all-electric cars such as the Nissan Leaf and Mini Cooper SE with scores in the high 60s. The Toyota RAV4 Prime, a plug-in hybrid SUV with 42 miles in range, got a score of 64. One gas hybrid, the Hyundai Elantra Blue, made the list as well — thanks to an efficient design and good mileage.

At the bottom of the list were large gas-guzzling trucks such as the Ford F-150 Raptor R, with scores in the 20s. So was one electric car: the Hummer EV, which weighs 9,000 pounds and scored a 29.

Plug-in hybrids haven’t gotten too much attention in the race to electrify the nation’s cars. The vehicles, which can travel on electric power alone for 20 to 50 miles, have a few downsides. Drivers are forced to maintain both an electric motor and a gas-powered engine; plug-in hybrids also generally can’t be charged at super-fast charging stations. EV purists scorn them as a meager halfway step toward all-electric cars.

But for some drivers, plug-in hybrids can be a happy medium between converting to all-electric or sticking with gas. Many plug-in hybrids allow drivers to do most of their regular driving on electricity (the average American drives only about 27 miles a day) and switch over to gas for longer road trips. That allows plug-in hybrid owners to avoid wrestling with America’s complicated and faulty charging infrastructure.

The Prius Prime outranked its competitors, Huether said, because of its small battery — which lowers the emissions and pollution associated with manufacturing — and its high efficiency. The vehicle’s battery is less than one-tenth the size of the battery on the monstrous Hummer EV. That means fewer emissions in making the battery, and fewer rare minerals to mine and extract.

Jessika Trancik, a professor at MIT’s Institute for Data, Systems, and Society who was not involved in the report, said that the GreenerCars study used a standard methodology to analyze the environmental harm of cars, but that it is hard to predict how much drivers actually run their plug-in hybrids on electricity. “In the U.S., it often comes down to whether they have an easy way to plug in while they’re at home,” she said.

The GreenerCars report assumed that Prius Prime drivers were using electricity for a little over 50 percent of their driving, based on data from the Society of Automotive Engineers. For drivers with charging available at home, that might be an underestimate.

But Gil Tal, director of the Electric Vehicle Research Center at the University of California at Davis, said some studies show that drivers use their plug-in hybrids as regular hybrids, almost never charging them. That could undercut the findings from the GreenerCars report. “I don’t think the Prius Prime is the greenest,” Tal said. “If you can buy a full-electric, it’s always the best, regardless of the few points of difference here.”

As more wind and solar power are plugged into the grid, Tal added, electric cars will get cleaner and cleaner over time. “And your gas car will be worse over the years,” he said.

Huether says the most important thing is that drivers can find the most environmentally friendly option that suits them — whether that’s a plug-in hybrid, conventional hybrid or all-electric car. “Some folks are still concerned about the charging infrastructure,” he said. “But we still want them to have a very green option.”