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Plug-in hybrid cars emit nearly 5x greater global warming emissions than official data show, according to a recent report.

Widening Discrepancy Between Lab and Actual CO2 Output

Data shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy group. That contrasts sharply with laboratory tests, which suggested a three-quarters decrease in pollution.

Researchers examined data from onboard energy use meters of eight hundred thousand cars sold in Europe between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” said a senior researcher involved in the report. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in battery mode compared to total distance. They found that only a quarter of travel was done in EV mode, whereas lab assumptions assumed 84%.

Additionally, when running in electric mode, emission levels were significantly higher than lab projections. That occurred because electric motors were not strong sufficient to function independently, resulting to combustion motors burning fossil fuels for almost one-third of the distance covered in EV mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed several large automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more per year in operating costs than is estimated under lab tests.

“The strong statements that automakers often promote about their PHEV cars are obviously way off the truth,” stated a transport 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 better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy discussions as automakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the car industry and opposition from EU countries with significant automotive industries.

Several high-level politicians have proposed PHEVs as a possible “flexibility” option to include in the legislation.

One external energy policy expert, who was not involved with the research, called the report a “highly valuable addition” after years in which segments of the automotive industry argued there was insufficient information to properly assess actual CO2 output.

“The results demonstrate, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they stated. “All policy changes concerning PHEVs should be implemented with utmost caution and considering this evidence.”