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PHEVs release almost 5x more global warming emissions than lab-reported data show, as per a recent analysis.

Growing Gap Between Lab and Actual Emissions

Data reveals that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy group. That differs sharply with lab tests, which assumed a three-quarters decrease in emissions.

Researchers examined data from onboard fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a senior analyst involved in the study. “This gap is growing and creates a serious issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery mode compared to overall distance. The team found that only a quarter of driving was done in EV mode, whereas official estimates suggested over four-fifths.

Additionally, when running in electric mode, emission levels were significantly higher than official estimates. This happened because EV motors were insufficiently powerful enough to operate independently, leading to engines burning fossil fuels for nearly a third of the distance completed in EV mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions allowed four large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend about €500 extra per year in operating costs than would be assumed under lab tests.

“The bold statements that automakers often promote about their PHEV vehicles are obviously far from the mark,” stated a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Industry Pressure

Hybrid cars have lately been brought back into political debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from member states with large car industries.

Several senior politicians have proposed PHEVs as a potential “flexibility” option to include in the regulation.

An external energy economics expert, who was not involved with the research, called the analysis a “highly valuable addition” after years in which parts of the car industry argued there was too little data to accurately evaluate real-world emissions.

“These findings demonstrate, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert said. “Any policy changes regarding PHEVs should be implemented with utmost care and considering this data.”