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PHEVs emit almost five times more planet-heating emissions than lab-reported data show, as per a recent report.

Growing Discrepancy Between Official and Actual Emissions

Statistics reveals that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a non-profit group. This contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers examined data from onboard energy use meters of eight hundred thousand cars registered in the EU between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” said a senior analyst involved in the study. “That gap is widening and creates a serious issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery power relative to total mileage. They found that just a quarter of travel was completed in EV mode, whereas official estimates suggested over four-fifths.

Even, when operating in electric mode, pollution levels were well above lab estimates. This happened because electric motors were not strong enough to operate alone, resulting to engines using fossil fuels for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV emissions allowed several large carmaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 more annually in operating costs than is estimated under lab tests.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought back into policy debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with large automotive industries.

Several senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

An independent energy economics expert, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which parts of the automotive sector claimed there was insufficient data to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost caution and considering this evidence.”