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Plug-in hybrid electric vehicles emit nearly five times more global warming pollution than lab-reported figures show, as per a new analysis.

Growing Gap Between Official and Real-World CO2 Output

Statistics shows that PHEVs release only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy organization. This contrasts sharply with lab tests, which assumed a 75% reduction in pollution.

Analysts examined information from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” said a lead analyst involved in the report. “This gap is widening and poses a serious issue. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Factors Driving the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode compared to overall mileage. The team determined that just 27% of travel was completed in electric mode, while lab assumptions suggested 84%.

Even, when operating in electric mode, pollution levels were well above lab estimates. That happened because EV motors were insufficiently powerful enough to operate alone, resulting to engines using gasoline for nearly a third of the travel covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed several large automaker companies to escape more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 more per year in running expenses than would be assumed under laboratory conditions.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” commented a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have recently been drawn back into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the car industry and resistance from member states with significant automotive industries.

Several senior politicians have suggested PHEVs as a possible “compromise” solution to include in the regulation.

One independent energy policy expert, who was not involved with the study, called the report a “highly valuable addition” after years in which segments of the automotive sector argued there was insufficient data to properly evaluate actual CO2 output.

“These findings demonstrate, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” they stated. “Any regulatory changes regarding PHEVs should be implemented with extreme caution and considering this data.”