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Plug-in hybrid cars release almost five times greater planet-heating pollution than lab-reported figures indicate, as per a recent report.

Widening Gap Between Lab and Actual Emissions

Statistics shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a advocacy organization. That differs significantly with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers examined data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a senior analyst involved in the study. “That gap is widening and poses a significant issue. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Key Reasons Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of miles travelled in electric power compared to overall mileage. The team found that just 27% of travel was completed in EV mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than lab estimates. This happened because EV motors were insufficiently powerful enough to function alone, leading to engines using gasoline for almost a third of the travel covered in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled several large automaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay about €500 extra per year in operating expenses than is estimated under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are obviously far from the mark,” stated a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have lately been brought back into political discussions as automakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with large car manufacturing.

Several high-level politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

One external energy economics expert, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which segments of the automotive sector argued there was too little information to properly assess actual emissions.

“These findings show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional cars,” they said. “All policy changes regarding PHEVs should be implemented with utmost caution and in the light of this data.”