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PHEVs produce nearly 5x more planet-heating emissions than official figures show, according to a new analysis.

Growing Gap Between Lab and Actual Emissions

Data reveals that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to research carried out by a advocacy organization. This differs significantly with laboratory tests, which suggested a 75% reduction in pollution.

Researchers studied information from onboard fuel consumption meters of 800,000 cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” said a senior researcher involved in the report. “This gap is growing and creates a serious problem. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in electric mode compared to total mileage. The team found that only a quarter of driving was completed in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab projections. This occurred because electric motors were insufficiently powerful enough to operate independently, leading to combustion motors using fossil fuels for nearly one-third of the travel covered in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed several large carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more annually in operating costs than would be assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously far from the mark,” commented a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Hybrid vehicles have lately been brought back into policy debates as automakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large automotive manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” solution to introduce in the legislation.

One independent energy economics expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which parts of the automotive sector argued there was insufficient data to properly evaluate actual emissions.

“The results show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert stated. “Any policy adjustments regarding PHEVs should be implemented with utmost care and in the light of this evidence.”