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PHEVs produce nearly 5x more planet-heating pollution than official figures indicate, as per a recent report.

Growing Discrepancy Between Lab and Actual Emissions

Data reveals that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit organization. That differs significantly with lab tests, which assumed a 75% decrease in pollution.

Researchers studied data from onboard energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a senior analyst participating in the report. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Key Factors Driving the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric mode compared to overall mileage. The team found that only 27% of driving was done in electric mode, whereas official assumptions assumed over four-fifths.

Additionally, when operating in electric mode, emission levels were significantly higher than lab projections. This happened because electric motors were insufficiently powerful enough to function alone, resulting to engines using gasoline for almost a third of the distance completed in EV mode.

Policy and Economic Implications

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

Furthermore, owners of PHEVs would spend about €500 more annually in operating costs than is estimated under lab tests.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been drawn again into political discussions as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with significant automotive industries.

Some senior politicians have proposed PHEVs as a potential “flexibility” solution to introduce in the regulation.

An independent energy economics expert, who was not involved with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the car sector claimed there was insufficient information to properly assess real-world CO2 output.

“The results demonstrate, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be implemented with utmost caution and considering that data.”