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PHEVs emit nearly five times greater global warming emissions than lab-reported data indicate, according to a new report.

Widening Gap In Lab and Actual CO2 Output

Statistics reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy group. This contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined data from in-vehicle energy use monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a lead analyst participating in the study. “That discrepancy is growing and creates a significant issue. As a result, PHEVs emit nearly as much as gasoline vehicles.”

Key Factors Driving the Discrepancy

Researchers linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery power compared to total mileage. They found that just 27% of driving was done in electric mode, whereas lab assumptions suggested 84%.

Even, when operating in EV mode, emission amounts were significantly higher than official projections. That occurred because electric motors were not strong enough to function alone, resulting to combustion motors using gasoline for nearly a third of the distance covered in electric mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV CO2 output allowed four major carmaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would pay about €500 more annually in running expenses than is assumed under lab tests.

“The bold claims that automakers like to make about their PHEV cars are obviously far from the mark,” stated a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and opposition from EU countries with large automotive industries.

Some high-level officials have proposed PHEVs as a potential “flexibility” solution to include in the legislation.

An external energy policy specialist, who was not involved with the study, called the analysis a “very useful addition” after years in which parts of the automotive industry claimed there was insufficient data to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with extreme care and in the light of that data.”