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Plug-in hybrid electric vehicles produce almost five times greater global warming emissions than lab-reported figures show, as per a recent report.

Widening Discrepancy In Lab and Real-World Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a non-profit organization. That contrasts sharply with lab estimates, which suggested a 75% reduction in pollution.

Analysts examined data from in-vehicle fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a lead analyst involved in the study. “That discrepancy is widening and poses a significant issue. Consequently, PHEVs pollute almost as much as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric mode compared to overall mileage. They found that only 27% of driving was completed in electric mode, whereas lab assumptions suggested 84%.

Additionally, when operating in electric mode, pollution amounts were significantly higher than lab projections. That occurred because EV motors were not strong enough to function alone, leading to engines burning gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled four large automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

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

“The strong statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have recently been brought back into policy debates as automakers have lobbied the European Union to relax CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with large automotive manufacturing.

Some high-level politicians have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

An external energy economics expert, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which segments of the car sector claimed there was too little information to properly assess actual emissions.

“These findings show, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they stated. “Any regulatory changes regarding PHEVs should be implemented with extreme care and considering this data.”