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PHEVs emit almost five times greater planet-heating pollution than official data indicate, as per a new report.

Growing Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs emit just 19% lower CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. This differs significantly with lab tests, which suggested a 75% reduction in emissions.

Researchers studied information from in-vehicle energy use meters of 800,000 cars sold in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” said a lead analyst participating in the study. “That gap is widening and creates a serious issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total distance. They found that just 27% of travel was completed in EV mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution levels were significantly higher than official projections. That occurred because electric motors were not strong sufficient to function alone, leading to combustion motors burning gasoline for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions allowed several large carmaker groups to escape over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra annually in operating costs than is assumed under laboratory conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn again into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with large car manufacturing.

Several high-level officials have suggested plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

An independent energy economics expert, who was not involved with the study, described the report a “very useful addition” after a long period in which segments of the automotive sector argued there was insufficient information to properly evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional vehicles,” the expert said. “All regulatory changes regarding PHEVs should be implemented with extreme caution and in the light of this evidence.”