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In the right circumstances, could a hybrid car be "cleaner" than an electric vehicle?
Fully electric vehicles are usually the cleanest choice, but it is possible for a hybrid vehicle to create even less climate pollution, depending how and where they're manufactured and driven.
January 14, 2025
Electric vehicles (EVs), research has consistently shown, produce fewer climate-warming emissions compared to cars that burn gasoline or diesel. But could hybrid vehicles be a better deal for the climate than full EVs? “You can construct those cases and get that answer,” says Sergey Paltsev, deputy director of the MIT Center for Sustainability Science and Strategy and senior research scientist at the MIT Energy Initiative. However, it might require cherry-picking data to find a very specific set of circumstances.
There are two types of hybrid vehicles, both of which run on a mix of electricity from a battery (like an EV) and a gasoline engine (like an ordinary car). A traditional hybrid vehicle, like a Toyota Prius, carries a battery that recharges while the car’s engine runs. This energy is delivered to the wheels through electric motors, allowing the car to switch quickly between electric and gas power depending on driving conditions. A plug-in hybrid vehicle (PHEV), meanwhile, is essentially a full EV with a gas engine as a backup. This allows it to get by with a much smaller battery than a pure EV: when the battery runs out, the gas engine takes over.
No matter the vehicle, driving on gasoline virtually always does more to affect the climate than driving on battery power. That’s partly because burning gasoline in an engine directly produces climate-warming carbon dioxide (CO2). But it’s also because electric motors are much more efficient than engines at turning energy into driving power. For example, consider an EV charged in West Virginia, where most electricity comes from burning coal—itself a major source of CO2. This car still produces less CO2 per mile driven than a gas-powered car, because it gets so much mileage out of every bit of electricity in its battery.1
So how could a hybrid, which uses gasoline at least part of the time, ever be cleaner than an EV? To know which vehicle is truly least damaging to the climate, you also need to factor in all the emissions created over the car’s lifetime.2 And that’s where the math gets tricky.
If you look at a line graph of an EV’s lifetime CO2 emissions, you’ll see there’s a big bump at the beginning. That’s because building EVs creates more emissions than building gasoline cars, due to the mining and manufacturing needed to make their large batteries. After this big initial bump, there’s a gentle slant as the EV creates a modest amount of emissions every time it charges up, because electricity currently is not emissions-free.
Meanwhile, a gas car’s graph would start with a smaller bump, but then slope dramatically upward as it spends its entire driving life—more than a decade on average—burning gasoline and releasing CO2. After a few thousand miles of driving, the gas car’s emissions overtake the EV’s and keep rising.
Hybrids, both traditional and plug-in, fall in the middle. Because their batteries are smaller than an EV’s, their graphs start with a medium-sized bump. This makes it possible to draw up scenarios where a hybrid is less climate-polluting than an EV. For example, a person who does most of their driving within a few miles of home could own a plug-in hybrid and rely on electric power nearly all the time. In this case, the PHEV is, in practice, a true EV, but with a smaller battery. With fewer manufacturing emissions, this hybrid would almost by definition be "cleaner" than a full EV—although that calculus could change quickly if the owner began to use their hybrid’s gas engine more often.
However, Paltsev says, driving habits aren’t the most important factor when comparing hybrids to EVs. The bigger questions are: How clean is your electricity, and how dirty is battery manufacturing?
Let’s return to our EV charged in West Virginia. It drives cleaner than a gasoline car, but not a lot cleaner. In 2019, Paltsev worked on a study that concluded that, once you factor in manufacturing, this West Virginia EV will only barely be cleaner than a gasoline car. Here, a traditional hybrid would actually be 30% cleaner than a full EV.1
If you live somewhere that’s highly reliant on coal power, then, an EV could be seen as a bet that the power mix will get cleaner over your car’s lifetime. And, Paltsev points out, this would not be a crazy bet: the United States, like many other countries, is rapidly adding clean solar and wind power while phasing out coal. Already, most places are not like West Virginia, and we can expect EVs to be cleaner than hybrids and continue to get cleaner in the years to come.
Battery manufacturing is harder to evaluate. For one thing, Paltsev says, many estimates of the emissions created by battery manufacturing are based on data that goes back to the previous decade—and may be outdated for an industry changing so quickly. It’s also not universally agreed what counts as manufacturing, and studies are not consistent. Any fair study of this question will have to include the emissions from mining the metals that go into a battery—but what about the emissions from building the mining equipment? “It really depends where you draw the boundaries for your comparison,” he says.
Paltsev says a few studies, using high-end estimates for the amount of climate pollution created by battery manufacturing, have found plug-in hybrids to be cleaner than EVs. In his estimate, those figures are too high—perhaps double the likely emissions of today’s cleanest EV battery production—but it’s not surprising that researchers studying a hard question in a fast-changing environment can reach different answers.
Although Paltsev’s research is clear that EVs are the best choice for the climate, he would never say they’re the only good choice. Driving a hybrid can dramatically reduce climate pollution compared to owning a gasoline-only vehicle. If that’s the right choice for some drivers, then he encourages them to make it. “Every ton of CO2 that we can reduce matters,” he says.
Thank you to many readers who sent in related questions, including David Byrne of Dublin, Ireland, Claire Kowalchik of Emmaus, Pennsylvania, Shreenivas Mate of Ventura, California, Sherry Morgan of South Deerfield, Massachusetts, Peter North of Woolwich, Maine, and Jimmy Voorhis of Boulder, Colorado.
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1 MIT Energy Initiative: Insights Into Future Mobility, November 2019.
2 Argonne National Laboratory: "Cradle-to-grave lifecycle analysis of U.S. light-duty vehicle-fuel pathways: a greenhouse gas emissions and economic assessment of current (2020) and future (2030-2035) technologies," November 1, 2023.
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