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Plug-in hybrid cars emit nearly five times greater global warming emissions than official figures show, as per a new analysis.

Widening Discrepancy In Official and Actual Emissions

Data reveals that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit organization. That contrasts significantly with lab estimates, which assumed a 75% reduction in emissions.

Analysts examined information from onboard energy use meters of eight hundred thousand cars registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” said a senior analyst involved in the study. “This discrepancy is growing and creates a serious problem. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in battery mode relative to overall mileage. The team found that just a quarter of travel was completed in electric mode, while official estimates suggested 84%.

Even, when running in electric mode, emission amounts were well above official projections. That happened because EV motors were insufficiently powerful enough to operate alone, leading to engines using fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions allowed several major automaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay about €500 extra per year in running expenses than is assumed under laboratory conditions.

“The strong statements that automakers often promote about their plug-in hybrid cars are clearly far from the truth,” commented a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Discussion and Automotive Pressure

Hybrid cars have recently been drawn again into policy debates as carmakers have pressed the EU to relax CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and resistance from EU countries with large car industries.

Some high-level officials have suggested PHEVs as a possible “flexibility” option to introduce in the legislation.

An independent energy economics specialist, who was not involved with the study, called the report a “highly valuable addition” after a long period in which parts of the car industry claimed there was too little data to properly evaluate actual emissions.

“The results show, without question, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel vehicles,” the expert stated. “Any regulatory adjustments concerning PHEVs should be made with utmost caution and considering this evidence.”