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Plug-in hybrid cars emit nearly five times greater global warming emissions than lab-reported figures indicate, according to a recent analysis.

Widening Discrepancy Between Official and Real-World Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a non-profit group. This contrasts sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Analysts studied information from in-vehicle energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” stated a lead researcher involved in the report. “That gap is growing and poses a significant problem. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode relative to total mileage. They found that just a quarter of travel was completed in electric mode, while official estimates assumed 84%.

Additionally, when operating in electric mode, pollution levels were significantly higher than official projections. This happened because electric motors were not strong enough to operate independently, resulting to engines burning gasoline for nearly a third of the travel completed in EV mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed several large automaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra annually in operating costs than is estimated under laboratory tests.

“The bold claims that automakers often promote about their PHEV cars are obviously way off the truth,” stated a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been brought again into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with significant automotive manufacturing.

Some senior politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the legislation.

An independent energy economics specialist, who was unaffiliated with the study, described the analysis a “very useful contribution” after a long period in which parts of the car sector argued there was too little information to properly assess actual emissions.

“These findings show, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and in the light of this data.”