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Plug-in hybrid cars emit almost five times more global warming emissions than official figures indicate, as per a new report.

Growing Discrepancy In Official and Actual Emissions

Data shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy organization. That contrasts sharply with lab tests, which suggested a three-quarters reduction in emissions.

Researchers examined data from onboard energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” stated a senior researcher participating in the report. “This gap is widening and poses a significant issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode relative to overall mileage. They determined that just a quarter of travel was done in EV mode, while lab assumptions suggested 84%.

Even, when operating in electric mode, pollution levels were significantly higher than official estimates. That happened because electric motors were not strong enough to function alone, leading to engines burning fossil fuels for almost a third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed four major carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in operating costs than is assumed under lab conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” stated a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have pressed the EU to weaken CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant automotive manufacturing.

Some senior officials have suggested PHEVs as a possible “compromise” solution to include in the legislation.

An external energy economics expert, who was unaffiliated with the study, called the analysis a “very useful addition” after years in which segments of the automotive sector claimed there was too little data to properly assess real-world emissions.

“The results show, without question, that the difference in lab and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” they said. “Any regulatory changes regarding PHEVs should be made with utmost caution and in the light of that data.”