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Plug-in hybrid electric vehicles emit nearly five times greater global warming pollution than official figures show, according to a recent report.

Growing Gap In Lab and Real-World CO2 Output

Data reveals that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel cars, based on analysis carried out by a non-profit organization. That contrasts significantly with lab estimates, which suggested a three-quarters decrease in pollution.

Analysts studied information from onboard energy use meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a lead researcher participating in the report. “This gap is growing and creates a significant issue. As a result, PHEVs pollute almost as much as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery mode relative to total mileage. They found that only 27% of travel was completed in EV mode, while official estimates suggested over four-fifths.

Even, when running in EV mode, pollution levels were well above official estimates. That happened because EV motors were insufficiently powerful sufficient to function alone, leading to engines burning gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV CO2 output allowed several large automaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more per year in operating costs than is estimated under laboratory tests.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” stated a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are little better than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been brought again into policy debates as carmakers have pressed the European Union to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and resistance from EU countries with significant car industries.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” solution to include in the legislation.

One external energy policy specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which segments of the automotive industry claimed there was insufficient data to accurately assess actual emissions.

“The results demonstrate, without question, that the difference between official and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel cars,” the expert said. “Any policy adjustments regarding PHEVs should be made with extreme caution and considering that data.”