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Plug-in hybrid electric vehicles emit nearly 5x greater global warming emissions than official figures show, as per a new analysis.

Growing Gap Between Lab and Actual CO2 Output

Data reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a non-profit group. This differs sharply with laboratory tests, which assumed a 75% decrease in pollution.

Researchers studied information from onboard fuel consumption meters of eight hundred thousand cars sold in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” stated a senior analyst involved in the report. “That discrepancy is growing and poses a significant issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in battery mode compared to total mileage. The team determined that just a quarter of driving was completed in EV mode, while lab estimates assumed 84%.

Even, when running in EV mode, pollution levels were significantly higher than official estimates. This happened because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors using fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Economic Implications

According to calculations, the underestimation of PHEV emissions allowed four large carmaker companies to escape over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 extra per year in operating expenses than is estimated under lab tests.

“The bold claims that automakers like to make about their plug-in hybrid cars are clearly far from the truth,” stated a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been brought back into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with significant car manufacturing.

Some senior officials have proposed PHEVs as a possible “compromise” option to introduce in the regulation.

An independent energy policy expert, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the car sector claimed there was insufficient data to properly evaluate actual emissions.

“The results demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert said. “Any policy changes regarding PHEVs should be implemented with utmost care and considering this evidence.”