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Plug-in hybrid cars release almost 5x more planet-heating pollution than lab-reported data show, as per a recent report.

Growing Gap In Official and Real-World Emissions

Data shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel vehicles, according to research conducted by a non-profit organization. This contrasts sharply with lab estimates, which suggested a 75% decrease in emissions.

Analysts studied information from in-vehicle energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” said a senior analyst involved in the report. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode compared to overall mileage. They determined that just 27% of driving was done in EV mode, whereas official estimates assumed 84%.

Even, when running in EV mode, emission levels were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful enough to operate independently, leading to combustion motors burning fossil fuels for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several major automaker groups to escape over €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 extra per year in operating expenses than would be assumed under lab conditions.

“The strong statements that manufacturers often promote about their PHEV cars are clearly far from the mark,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been brought again into policy discussions as automakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large automotive industries.

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

An independent energy policy specialist, who was unaffiliated with the research, described the analysis a “very useful addition” after a long period in which parts of the car industry claimed there was insufficient data to properly assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or conventional cars,” they said. “Any regulatory adjustments concerning PHEVs should be made with extreme care and in the light of this evidence.”