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Plug-in hybrid cars produce nearly five times more planet-heating emissions than lab-reported figures show, as per a recent analysis.

Widening Gap In Official and Actual Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a non-profit group. This differs sharply with lab tests, which assumed a 75% reduction in emissions.

Researchers studied information from onboard energy use monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a lead researcher participating in the report. “That gap is widening and creates a serious problem. As a result, PHEVs emit almost as much as petrol cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power relative to total mileage. They found that just 27% of travel was completed in electric mode, while lab assumptions suggested 84%.

Even, when running in electric mode, emission levels were well above official estimates. That occurred because electric motors were not strong sufficient to function independently, resulting to combustion motors using gasoline for nearly a third of the distance covered in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions allowed several major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs would spend approximately €500 extra per year in running costs than would be estimated under lab tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have lately been drawn back into political discussions as automakers have pressed the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car sector and resistance from member states with significant automotive manufacturing.

Several senior officials have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

An external energy policy specialist, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which parts of the automotive industry claimed there was insufficient information to properly assess actual CO2 output.

“The results show, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel vehicles,” the expert stated. “All policy adjustments regarding PHEVs should be made with extreme caution and considering this evidence.”