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Plug-in hybrid electric vehicles emit almost five times more global warming emissions than lab-reported figures show, as per a recent analysis.

Widening Discrepancy In Official and Real-World Emissions

Statistics shows that PHEVs release only 19% lower CO₂ than traditional petrol and diesel cars, according to analysis carried out by a non-profit organization. That differs significantly with lab tests, which suggested a 75% decrease in emissions.

Analysts examined data from onboard energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a lead researcher involved in the study. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs pollute nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode relative to overall mileage. They determined that just a quarter of driving was done in electric mode, while official assumptions suggested over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official projections. That happened because EV motors were not strong enough to function independently, leading to engines using fossil fuels for nearly a third of the travel covered in electric mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed several major carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 extra annually in running expenses than would be assumed under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV cars are clearly way off the truth,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been brought again into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large automotive industries.

Some high-level officials have suggested plug-in hybrids as a potential “compromise” solution to include in the legislation.

One external energy economics expert, who was not involved with the study, called the report a “highly valuable addition” after years in which parts of the automotive sector argued there was too little information to properly assess real-world emissions.

“These findings demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional cars,” the expert said. “All regulatory adjustments concerning PHEVs should be made with utmost caution and considering this data.”