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Plug-in hybrid cars emit almost 5x more global warming pollution than official figures show, as per a new report.

Growing Gap Between Official and Actual CO2 Output

Statistics reveals that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a non-profit group. This differs sharply with lab tests, which assumed a three-quarters decrease in emissions.

Analysts studied data from onboard fuel consumption meters of 800,000 cars sold in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” stated a lead analyst involved in the study. “This gap is growing and creates a serious problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery power relative to total mileage. They found that only 27% of travel was completed in EV mode, whereas lab assumptions assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than official estimates. That occurred because electric motors were not strong sufficient to operate alone, resulting to combustion motors using fossil fuels for almost a third of the distance covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 extra annually in running expenses than would be estimated under laboratory conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Industry Pressure

Plug-in hybrid cars have lately been drawn again into political discussions as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with large car manufacturing.

Several senior politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

One external energy economics expert, who was unaffiliated with the study, called the report a “highly valuable contribution” after years in which segments of the automotive industry argued there was insufficient data to accurately evaluate real-world CO2 output.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be implemented with utmost care and in the light of that data.”