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Plug-in hybrid cars produce nearly five times more planet-heating pollution than official data show, according to a recent analysis.

Widening Discrepancy In Official and Real-World Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit group. That contrasts significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts studied information from onboard energy use monitors of 800,000 vehicles registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a senior analyst involved in the report. “That discrepancy is growing and creates a serious problem. As a result, PHEVs emit almost as much as petrol cars.”

Key Reasons Behind the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to total distance. They found that just a quarter of travel was completed in EV mode, while official assumptions assumed 84%.

Even, when running in EV mode, pollution amounts were significantly higher than official estimates. That occurred because electric motors were not strong enough to function alone, resulting to combustion motors burning fossil fuels for nearly a third of the distance completed in electric mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV emissions enabled several large carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay about €500 extra per year in operating expenses than would be assumed under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously far from the mark,” stated a automotive analyst. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been drawn again into political discussions as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with large car manufacturing.

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

One independent energy economics expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after a long period in which parts of the car industry claimed there was insufficient data to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or diesel vehicles,” the expert said. “Any policy adjustments concerning PHEVs should be made with extreme care and considering this data.”