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PHEVs release nearly 5x greater planet-heating emissions than lab-reported data show, as per a new analysis.

Growing Discrepancy Between Official and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel cars, according to analysis conducted by a non-profit group. This differs significantly with laboratory estimates, which assumed a three-quarters reduction in pollution.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” said a senior researcher participating in the report. “That discrepancy is widening and poses a significant problem. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles driven in electric power compared to overall distance. The team found that only a quarter of travel was done in EV mode, while lab assumptions assumed 84%.

Additionally, when operating in EV mode, pollution amounts were well above lab estimates. This occurred because electric motors were not strong sufficient to function alone, leading to combustion motors burning fossil fuels for almost a third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could spend about €500 extra per year in operating expenses than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV cars are clearly way off the mark,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been drawn back into policy debates as carmakers have pressed the EU to weaken CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with significant car industries.

Some high-level officials have proposed plug-in hybrids as a potential “flexibility” solution to include in the legislation.

An external energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was too little information to accurately evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional vehicles,” they stated. “All policy adjustments regarding PHEVs should be implemented with extreme caution and in the light of this data.”