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Plug-in hybrid electric vehicles release almost 5x more global warming pollution than lab-reported figures indicate, according to a recent analysis.

Growing Gap Between Lab and Actual Emissions

Statistics reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy group. This contrasts significantly with laboratory tests, which assumed a 75% reduction in pollution.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a senior analyst involved in the study. “This gap is widening and poses a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Key Factors Behind the Discrepancy

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric power relative to total mileage. They determined that just 27% of driving was done in electric mode, whereas lab estimates suggested 84%.

Additionally, when operating in electric mode, pollution levels were significantly higher than official projections. That happened because electric motors were not strong sufficient to function independently, resulting to combustion motors using fossil fuels for nearly one-third of the distance completed in EV mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output enabled several large carmaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could pay approximately €500 extra annually in running costs than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the truth,” commented a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid cars have recently been brought back into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large automotive industries.

Several senior officials have suggested PHEVs as a possible “compromise” option to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after years in which parts of the automotive industry claimed there was too little information to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the difference between lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and considering that evidence.”