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PHEVs release almost five times more planet-heating pollution than official figures indicate, as per a new report.

Growing Gap Between Lab and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, based on analysis carried out by a non-profit organization. This contrasts sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a lead researcher participating in the report. “This discrepancy is growing and poses a serious problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to overall mileage. They found that only a quarter of driving was completed in EV mode, whereas lab estimates suggested over four-fifths.

Even, when running in electric mode, emission levels were significantly higher than lab projections. This occurred because EV motors were not strong enough to function alone, leading to combustion motors using gasoline for almost a third of the distance covered in EV mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed four major automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

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

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” commented a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into political debates as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from member states with significant automotive manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” option to include in the regulation.

An external energy policy expert, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which parts of the car sector argued there was too little data to properly evaluate real-world emissions.

“These findings show, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional cars,” they stated. “Any regulatory changes concerning PHEVs should be made with extreme care and in the light of this evidence.”