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Plug-in hybrid cars release almost five times more planet-heating pollution than official figures show, as per a recent report.

Widening Discrepancy Between Lab and Real-World Emissions

Data shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, according to research conducted by a non-profit organization. This contrasts significantly with lab estimates, which assumed a 75% decrease in emissions.

Researchers examined information from onboard fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are decreasing,” said a senior researcher participating in the report. “This discrepancy is growing and creates a significant issue. As a result, PHEVs emit almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power relative to total mileage. They found that just a quarter of travel was done in electric mode, while lab assumptions suggested 84%.

Even, when operating in EV mode, emission amounts were well above lab projections. This happened because electric motors were not strong sufficient to operate independently, leading to combustion motors burning fossil fuels for almost a third of the distance completed in electric mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV emissions enabled several large carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 extra annually in operating expenses than is estimated under laboratory conditions.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have recently been drawn again into political discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with significant automotive industries.

Some senior officials have proposed PHEVs as a possible “flexibility” solution to introduce in the legislation.

One independent energy economics specialist, who was not involved with the study, called the report a “very useful addition” after a long period in which parts of the automotive sector claimed there was too little data to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or diesel cars,” the expert stated. “Any policy changes concerning PHEVs should be implemented with utmost caution and considering that evidence.”