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PHEVs produce almost 5x greater global warming pollution than official data show, according to a recent report.

Widening Discrepancy In Lab and Actual Emissions

Data reveals that PHEVs release only 19% less CO₂ than conventional petrol and diesel cars, according to research carried out by a advocacy organization. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied data from onboard fuel consumption meters of eight hundred thousand cars sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” said a senior analyst participating in the study. “This discrepancy is growing and poses a serious issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Factors Driving the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in battery power relative to overall distance. They found that just a quarter of travel was done in electric mode, while official estimates assumed over four-fifths.

Additionally, when operating in EV mode, pollution levels were well above lab projections. This happened because electric motors were not strong enough to function alone, leading to combustion motors burning gasoline for almost one-third of the distance covered in electric mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV emissions allowed several major carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more annually in running costs than would be estimated under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV cars are clearly far from the truth,” commented a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Hybrid cars have lately been drawn again into political debates as carmakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large automotive manufacturing.

Some high-level officials have proposed PHEVs as a potential “compromise” option to include in the regulation.

An independent energy policy expert, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after years in which segments of the automotive sector claimed there was too little information to properly evaluate real-world emissions.

“The results show, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” the expert stated. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of this evidence.”