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Plug-in hybrid electric vehicles produce nearly five times greater global warming emissions than official data indicate, as per a recent report.

Growing Gap In Lab and Real-World Emissions

Data shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel cars, according to analysis carried out by a non-profit group. That contrasts significantly with lab tests, which assumed a 75% decrease in emissions.

Analysts examined data from onboard energy use meters of 800,000 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 lab estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a lead analyst participating in the study. “This gap is growing and creates a serious issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Driving the Emissions Gap

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery power compared to overall distance. They found that only 27% of travel was completed in electric mode, whereas lab assumptions suggested 84%.

Even, when operating in electric mode, pollution amounts were significantly higher than official estimates. This happened because electric motors were not strong enough to function independently, resulting to combustion motors burning gasoline for nearly one-third of the distance completed in EV mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend approximately €500 extra per year in running costs than would be estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the truth,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with large car industries.

Some high-level officials have suggested PHEVs as a possible “compromise” option to introduce in the legislation.

An external energy policy expert, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which parts of the car industry argued there was insufficient data to properly assess actual CO2 output.

“These findings show, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional vehicles,” they stated. “Any policy adjustments regarding PHEVs should be implemented with utmost care and considering this evidence.”