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Plug-in hybrid electric vehicles release nearly 5x greater global warming emissions than official data show, as per a new report.

Widening Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a advocacy organization. This differs sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined data from in-vehicle energy use monitors of 800,000 cars sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Actual emissions are rising, while official figures are falling,” said a lead researcher participating in the study. “This discrepancy is growing and creates a significant problem. As a result, PHEVs pollute nearly as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode compared to overall distance. They found that only 27% of driving was done in EV mode, while lab estimates assumed over four-fifths.

Additionally, when operating in EV mode, emission levels were well above lab estimates. That occurred because electric motors were insufficiently powerful sufficient to function independently, leading to combustion motors using gasoline for nearly a third of the travel covered in EV mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV emissions enabled several major automaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more per year in running expenses than is assumed under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought again into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with large automotive manufacturing.

Several high-level politicians have suggested PHEVs as a potential “compromise” solution to introduce in the regulation.

One external energy economics expert, who was not involved with the research, called the analysis a “very useful contribution” after years in which segments of the car sector claimed there was too little information to accurately evaluate actual emissions.

“The results show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional cars,” they said. “Any policy adjustments concerning PHEVs should be made with extreme care and considering this data.”