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Plug-in hybrid cars produce almost five times greater global warming pollution than official data indicate, as per a recent report.

Widening Discrepancy Between Official and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, based on analysis conducted by a advocacy group. That contrasts sharply with lab estimates, which assumed a three-quarters decrease in pollution.

Analysts studied data from onboard energy use monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher participating in the study. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery power compared to total mileage. The team determined that only 27% of driving was completed in electric mode, while official estimates suggested 84%.

Even, when operating in electric mode, emission amounts were significantly higher than lab estimates. That occurred because EV motors were not strong sufficient to operate alone, leading to engines burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV emissions enabled several large automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

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

“The strong statements that automakers often promote about their PHEV cars are clearly way off the truth,” commented a automotive analyst. “Buyers are being misled into thinking that by buying 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 use, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Hybrid cars have lately been drawn again into policy debates as automakers have pressed the EU to weaken CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant car industries.

Several senior politicians have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

One external energy economics expert, who was not involved with the research, called the report a “very useful addition” after years in which parts of the car sector claimed there was too little information to properly assess actual CO2 output.

“The results show, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel vehicles,” they stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this data.”