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Plug-in hybrid cars emit nearly five times greater planet-heating pollution than lab-reported figures show, as per a recent report.

Widening Gap In Lab and Real-World CO2 Output

Data reveals that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, according to research carried out by a non-profit group. That differs sharply with lab tests, which suggested a three-quarters decrease in pollution.

Researchers examined information from onboard fuel consumption monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” said a lead analyst involved in the report. “This discrepancy is widening and creates a serious problem. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery power relative to overall distance. The team found that just a quarter of driving was done in electric mode, while lab estimates suggested 84%.

Even, when operating in EV mode, pollution amounts were significantly higher than official estimates. That happened because EV motors were not strong enough to operate independently, leading to combustion motors using fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV emissions allowed four major carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in running expenses than would be estimated under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Pressure

Hybrid vehicles have recently been brought again into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with significant automotive manufacturing.

Some senior officials have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

An independent energy economics expert, who was unaffiliated with the study, called the report a “highly valuable addition” after years in which segments of the car industry argued there was too little information to accurately evaluate actual CO2 output.

“These findings show, without question, that the difference in lab and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost care and in the light of that evidence.”