A major issue with plug-in hybrid vehicles (PHEVs) is that owners frequently fail to plug them in, which negates their potential climate and fuel efficiency benefits. Studies show that in both North American fleets and across Europe, PHEVs are often operated primarily on gasoline, resulting in real-world fuel consumption much higher than official estimates.
This is occurring even as hybrid sales surge due to slowing EV growth, with automakers promoting PHEVs as a transitional technology. However, the market is shifting, with some companies moving away from PHEVs toward other technologies like extended-range EVs, especially without strong regulatory incentives.
Main topics: Plug-in hybrid vehicles (PHEVs), real-world fuel efficiency and emissions, consumer charging behavior, hybrid vehicle market trends.
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The uncomfortable truth about hybrid vehicles
Plug-in hybrid owners rarely actually plug in their vehicles, practically negating the climate advantages of the technology.
The uncomfortable truth about hybrid vehicles
Plug-in hybrid owners rarely actually plug in their vehicles, practically negating the climate advantages of the technology.
How it started
Apologies to the Toyota Prius, but the first hybrid vehicle of note was the Semper Vivus, developed by Ferdinand Porsche (yes, that Porsche) way back in 1900. The Semper Vivus (Latin for “always alive”) used two combustion engines to power generators, which then fed electricity to motors inside the wheel hubs. The fact that it took modern engineers over a century to really appreciate the merging of internal combustion engines with electric power is a sign that ingenuity isn’t always a foregone conclusion in the automotive world.
Car companies are now trying to make up for lost time. Thanks to stagnating EV sales, hybrid vehicles are experiencing a major surge in popularity, with sales reaching record levels in 2024 and 2025. Hybrids are often held up as a stepping stone between the gas-driven cars of yesterday and the fully electric ones of tomorrow. Plug-in hybrids can offer 20–60 miles of electric-only driving for daily use, plus a gas engine for longer trips or when they can’t recharge. And as EV growth slows down, many automakers clearly see hybrids — and more specifically, plug-in hybrids (PHEV) — as a better fit for America’s fluctuating tastes. To give you a sense of where things are heading: The Toyota RAV4, America’s most popular vehicle of any type, is now only available in hybrid trims.
But cracks are starting to show in that market as well. Without strict fuel economy standards or EV tax credits, some automakers are shifting away from PHEVs. Jeep, for example, recently axed its PHEV models, despite being among the best-selling plug-in hybrids in the country. More recently, automakers are flocking to extended-range EVs (EREVs), which use small gas engines to recharge an EV-sized battery for added range.
But in order for plug-in hybrids to deliver on the promise of reduced emissions and better gas mileage, they need to be plugged in. Don’t plug them in, and you’re left with a heavier, potentially more polluting gas car.
How it’s going
On the question of whether people are actually plugging in their PHEVs, the research isn’t very promising. Numerous studies have shown that plug-in hybrid owners often neglect to charge their batteries, defeating the purpose of owning a vehicle that’s capable of driving emission-free.
In 2024, telematics and fleet management company Geotab analyzed 1,776 PHEVs used in commercial fleets. It found that North American fleet operators relied on gas for 86 percent of their total energy needs, suggesting they were failing to charge their batteries enough to run on electric-power only. Also PHEVs delivered an average fuel efficiency of 1.6 gallons every 62 miles (100 km), translating to about 37 miles per gallon. That’s only a smidge lower than the average fuel efficiency of gas equivalents, which consumed 1.8 gallons every 62 miles, or 33.1mpg.
Another study, released earlier this year by the Fraunhofer Institute, used onboard fuel consumption monitoring (OBFCM) data from 981,035 vehicles across Europe. With data from nearly a million cars, the study’s authors were able to draw conclusions about the behavior of plug-in hybrid owners. The results were fairly shocking: PHEVs require on average 6 liters of fuel per 100km, about three times more than previously claimed. The reason was that these vehicles were consuming fuel while also running on electric power — contrary to many manufacturers’ claims. And because drivers weren’t plugging their cars in, they’re not getting the fullest benefits from their powertrains, instead choosing to lug around a near-dead battery while using much more fuel than they should.
Toyota hybrid owners were the best, using electricity for 44 percent of the energy used for driving, suggesting these drivers were plugging in more often than not. The worst were Porsche owners, at just 0.8 percent, an average of 7kWh over two years. Ferdinand Porsche is likely rolling over in his grave.
What happens next
There’s still some hope for hybrid vehicles. Some automakers think they can compel their customers to get serious about plugging in by making a game out of it. For example, a prototype feature that gamifies charging was recently added to Toyota’s ChargeMinder app in the US and Japan. The feature used notifications, positive encouragement, and quizzes to help push owners toward better charging habits. In the US, PHEV owners were influenced to increase their charging frequency by 10 percent — and as a result, improved their own ownership satisfaction by 16 percentage points.
Other automakers are betting on extended-range electric vehicles, or EREVs, which essentially takes PHEVs and flips them around by starting with an EV-sized battery and platform and adding a small gas engine to recharge the battery. Of course, EREVs also need to be plugged in and refueled with gas, which leads us back to the same problem. It would seem that drivers are good at refueling or recharging, but when asked to do both, they stumble.
This leaves a lot of automakers in a sticky spot. Take General Motors, for example. The company’s Chevy Volt was among the best-selling plug-in hybrids in the US for years. But then GM scrapped it in 2018, opting instead to go all in on EVs. And while that’s resulted in some success — Chevy’s electric Blazer and Equinox are top sellers — it wasn’t enough to overcome the political tides that have consumed EV policy at the federal level. That’s forced GM to write off over $6 billion stemming from its EV investments, and now CEO Mary Barra says the company is actively exploring hybrids again.
But during a recent conference in Detroit, Barra gave voice to the uncomfortable truth about hybrids: “What we also know today with plug-in hybrids is that most people don’t plug them in,” she said. “So that’s why we’re trying to be very thoughtful about what we do from a hybrid and a plug-in hybrid perspective.”
By the way
- A recent study looked into whether PHEVs act as a “bridge” by helping consumers transition from gas to electric, or a “lock-in” insofar as they may stall the adoption of fully electric vehicles. The authors conclude that in a market without any subsidies, the presence of PHEVs actually slows down full electrification. Without intervention, EV market share is 24 percent lower after 20 years if PHEVs are an option, as many consumers “settle” for the hybrid instead of going fully electric.
- EVs still outperform hybrids in terms of life cycle emissions. Plug-in hybrids require more resources to manufacture and still rely partly on gasoline for driving, which equals carbon emissions. “From a climate perspective, pure electric vehicles are definitely better,” Alissa Kendall, a life cycle researcher at UC Davis, told me recently.
Read this
- InsideEVs asked automakers to share data about whether their plug-in hybrid customers actually plugged in. It didn’t go well.
- IEEE Spectrum makes the argument that the Toyota Prius, the first mainstream hybrid vehicle, was the most important car ever made.
- TechCrunch looks at the recent data around plug-in hybrids and concludes that the experiment has failed. Time to pull the plug.
Meridiano
