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Plug-in hybrid electric vehicles produce nearly five times more planet-heating pollution than official data indicate, according to a recent report.

Widening Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel cars, based on analysis conducted by a advocacy organization. This contrasts sharply with lab tests, which suggested a 75% reduction in pollution.

Researchers examined data from onboard energy use meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and creates a serious issue. As a result, PHEVs emit almost as much as gasoline vehicles.”

Key Factors Driving the Emissions Gap

Researchers attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode compared to total mileage. They determined that just 27% of driving was done in electric mode, whereas lab assumptions assumed 84%.

Additionally, when running in electric mode, pollution levels were significantly higher than official estimates. This happened because electric motors were insufficiently powerful enough to operate independently, resulting to engines using fossil fuels for nearly one-third of the travel covered in EV mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 more per year in operating expenses than is estimated under lab conditions.

“The bold statements that automakers often promote about their PHEV vehicles are obviously far from the mark,” commented a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car sector and resistance from EU countries with significant car manufacturing.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the regulation.

One independent energy economics expert, who was not involved with the study, described the report a “highly valuable contribution” after a long period in which parts of the automotive industry argued there was insufficient information to properly assess real-world CO2 output.

“These findings demonstrate, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost caution and considering that evidence.”