Electric vs. Plug-In Hybrid Cars: Which Is Greener?

The answer depends on how and where you drive.

Car charging at electric vehicle station
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Depending on the driving you do, a plug-in hybrid electric vehicle (PHEV) can be more environmentally friendly than a gasoline-powered vehicle and sometimes more than a battery electric vehicle (BEV or just EV). But the reverse is also true—in most instances, a plug-in hybrid is less environmentally friendly than an EV, and in many instances, worse than the gasoline vehicles it was meant to replace. In the coming years, there will be less and less of an incentive to buy a PHEV for either its convenience or its price.

Charging Convenience

One of the main reasons people choose plug-in hybrids over EVs is the fact that hybrids usually have a greater range. Potential buyers may want to reduce their carbon footprint, but they also want the convenience of being able to easily refuel their vehicle on a road trip.

Currently, charging infrastructure for electric vehicles can be spotty, leaving potential EV drivers with worries that they won't be able to get from Point A to Point B. While Tesla has installed a network of over 1,000 Supercharger locations in the United States and over 25,000 stations worldwide, currently only Tesla vehicles can use them.

That situation is soon about to change, however. CEO Elon Musk recently announced that Tesla will gradually open up its network to other vehicles in 2021, and the U.S. government has plans to rapidly install an EV charging network of 500,000 charging stations. With the political will, this can be done quickly: In the month of December 2020, China installed 112,000 EV charging stations, more than existed in the entire United States at the time.

Two vehicles at charging stations

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What About Plug-Less Hybrids?

This article does not consider plug-less hybrid electric vehicles (HEVs). While they have greater fuel efficiency and produce fewer greenhouse gas emissions than conventional gasoline-powered vehicles, they are essentially that: more efficient gasoline-powered vehicles, since their batteries cannot be charged from an electric outlet.

The case for the environmental superiority of electric vehicles over all gasoline-powered vehicles is quite clear. Over the entire life cycle of a vehicle, from raw materials to final disposal, driving an EV produces fewer pollutants and less greenhouse gas emissions than a comparable gasoline vehicle. Only in a few regions around the world today, in places where the vast majority of electricity is generated by coal, do HEVs produce fewer lifetime emissions than EVs, but this applies to no more than 5% of the world's transport.

Environmental Benefits

Under almost all circumstances, driving an electric vehicle is more environmentally beneficial than driving a plug-in hybrid. While electric vehicles provide the highest co-benefits of any vehicles in reducing air pollution and greenhouse gas emissions across most areas, in specific regions PHEVs provide greater environmental benefits than both gas-powered and electric vehicles.

This depends on two main factors: the amount of fossil fuel burned in order to produce the electricity that charges EVs, and the type of driving that a PHEV owner does. In short, the dirtier the electricity, the less environmental advantage electricity has over gasoline, or as one study stated (in the inverse): “the more the electricity sector is decarbonized, the greater the benefit of electrifying passenger vehicles.”

Dashboard monitor of energy consumption in an electric vehicle

Peter Dazeley / Getty Images

Driving habits also matter: the batteries of 2021 model plug-in hybrids have an average range of 29 miles, according to the U.S. EPA's Fuel Economy Guide Model Year 2021. Run the battery down, or run it at high speeds, and a PHEV runs on gasoline—and its emissions increase correspondingly.

A 2020 study from the International Council on Clean Transportation (ICCT) found that the majority of miles driven in a PHEV is not city driving but “extra-urban driving,” where the gasoline engine is more often used. Moreover, the same study found that PHEV owners do not charge their vehicles often enough to take advantage of their greater fuel efficiency. As a result, in real-world driving, PHEVs' electric motors are used for only half the amount of time that they are assumed to run. Their CO2 emissions are thus two to four times higher than they are approved for by regulators.

A separate 2020 study from Transport & Environment, finding similar disparities, also determined that because PHEVs are heavier than gasoline cars, they consume more fuel. Julia Poliscanova, a researcher at Transport & Environment, concluded that "from the perspective of environment and climate, today's plug-in hybrid technology is worse than what it is replacing."

The dilemma for potential plug-in hybrid buyers is that they want to reduce their carbon footprint while retaining the ability to drive longer distances than an EV allows on a single charge. But it's precisely long-distance driving that reduces the environmental benefits of plug-in hybrids.

Financial Considerations

In making “green” purchasing decisions, people also frequently have to weigh the environmental benefits against the potentially higher financial costs. The more expensive the purchase, the more those financial concerns can win out over environmental ones.

So if EVs are greener, do they come at a higher financial cost? Depending on the use case, a plug-in hybrid can be more economical to own than an electric vehicle, or vice versa. That is likely to change in the future since the current reasons for preferring a PHEV are areas where EVs are improving the fastest.

The engine and electric motor of a hybrid vehicle
Two means of propulsion means more maintenance.

dreamnikon / Getty Images

According to a 2021 study from the U.S. Department of Energy's Argonne National Laboratory, maintenance costs of an electric vehicle are lower than a plug-in hybrid: $0.061 per mile for an EV versus $0.090 for a PHEV, the latter being closer in price to vehicle solely powered by gasoline (at $0.101) than to an EV—which makes sense, considering that PHEVs still have internal combustion engines and battery technology that need to be maintained. The study also determined that an EV had on average better fuel economy than a PHEV: the equivalent of 91.9 miles per gallon for an EV compared to 62.96 mpg for a PHEV. Yet because of the higher purchasing cost of EVs, due largely to the price of their batteries, the study concluded that PHEVs on average have a lower total cost of ownership than electric vehicles.

Once again, however, much of this depends on driving habits. As noted, PHEVs are driven on gasoline in real-world studies far more often than has been previously estimated. This increases their fuel costs, which are already more than double those of an EV. According to the EPA's Fuel Economy Guide Model Year 2021, the average annual estimated fuel cost of a 2021-model EV was $667.50, while that of a PHEV was $1,481.73. (By comparison, a 2021-model gasoline car owner spends an average of $2,077.02 per year on fuel.)

Electricity is also far cheaper than gasoline. "In March 2021, the average price of a gallon of gasoline was $2.85, while the price of an equivalent amount of electricity was $1.16. And as the ICCT study cited above observed, PHEV's “real fuel consumption is two to four times higher than the test-cycle values.” The EPA's average annual fuel costs for PHEVs may be under-estimated.

Outlook for the Future

Colin McKerracher, the lead author of Bloomberg New Energy Finance (BNEF)'s Electric Vehicle Outlook 2021 states that plug-in hybrids “more and more look like a compliance strategy” which has allowed automakers to comply with emissions standards set by the European Union. As electric vehicles increasingly become the focus of auto manufacturers and as emissions standards are toughened, PHEVs could be phased out as too expensive and unable to compete with cleaner and lower-cost EVs. Because they have two fuel sources and two modes of propulsion, they “can never be cheaper on an upfront basis” than gasoline vehicles, and can never proportionally profit as much from the continued drop in lithium-ion battery prices as EVs can.

Once electric vehicles reach price parity with both PHEVs and fossil fuel vehicles, and once EV charging infrastructure is built out enough to make car buyers comfortable, it is likely that PHEVs will increasingly appear as a necessary but transitory shift to a cleaner, greener driving technology.

Some automakers have already seen the writing on the showroom walls. In 2019, facing declining sales in PHEVs, Volkswagen and General Motors announced plans to cut their development of PHEVs and turned their attention to EVs. In 2021, Ford announced that it would sell only EVs and PHEVs (in Europe) by 2026, and phase out PHEVs by 2030.

It seems increasingly clear that the future of transportation is fully electric. In the most mature electric vehicle markets, such as California and Norway, where robust charging networks and government incentives exist, that future is already here. How soon that future comes to you may depend on where you live.

View Article Sources
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