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Plug-in hybrid cars release almost 5x greater planet-heating emissions than official data show, as per a new report.

Growing Discrepancy Between Lab and Real-World CO2 Output

Statistics shows that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. This contrasts sharply with laboratory tests, which assumed a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a senior analyst participating in the study. “That discrepancy is widening and creates a serious problem. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in electric power relative to total distance. The team determined that just a quarter of travel was done in electric mode, whereas official estimates suggested 84%.

Additionally, when operating in EV mode, pollution levels were well above official estimates. This occurred because electric motors were not strong enough to operate independently, leading to engines burning fossil fuels for almost one-third of the travel covered in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV CO2 output allowed four large automaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more per year in running expenses than is estimated under lab conditions.

“The strong claims that automakers often promote about their PHEV vehicles are clearly way off the truth,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Pressure

Hybrid cars have recently been drawn back into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant car manufacturing.

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

One external energy economics expert, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which segments of the car sector argued there was insufficient data to accurately evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” the expert stated. “All regulatory adjustments regarding PHEVs should be implemented with extreme care and considering that data.”