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Plug-in hybrid electric vehicles produce nearly five times more planet-heating emissions than lab-reported figures show, as per a new analysis.

Growing Gap In Lab and Actual Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a advocacy organization. This contrasts significantly with lab tests, which suggested a 75% reduction in pollution.

Analysts examined information from onboard fuel consumption meters of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a senior analyst participating in the report. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Factors Behind the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the ratio of miles driven in electric power compared to overall mileage. The team determined that just a quarter of driving was done in EV mode, while lab assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than lab estimates. That occurred because electric motors were insufficiently powerful enough to function alone, leading to combustion motors burning fossil fuels for nearly a third of the distance covered in electric mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled several major carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more annually in running costs than would be estimated under laboratory tests.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large car industries.

Several high-level officials have suggested PHEVs as a possible “compromise” option to include in the regulation.

An independent energy policy expert, who was unaffiliated with the study, described the analysis a “highly valuable addition” after years in which parts of the car industry claimed there was too little data to properly evaluate real-world CO2 output.

“These findings show, without question, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with extreme care and considering this data.”