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PHEVs emit nearly five times greater global warming pollution than lab-reported figures show, according to a recent report.

Widening Gap Between Official and Real-World Emissions

Statistics shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, based on research carried out by a advocacy organization. This differs significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied data from onboard energy use monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a lead analyst involved in the report. “This gap is growing and creates a significant problem. As a result, PHEVs pollute almost as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in battery power compared to total mileage. They found that just 27% of driving was completed in electric mode, whereas lab assumptions assumed 84%.

Additionally, when running in EV mode, emission levels were significantly higher than lab estimates. This happened because EV motors were not strong sufficient to operate alone, resulting to engines using gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Economic Consequences

According to estimates, the underestimation of PHEV CO2 output enabled four major carmaker groups to escape over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more per year in operating expenses than is estimated under lab tests.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are obviously way off the mark,” stated a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been drawn back into policy debates as automakers have pressed the European Union to weaken CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant car industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

One independent energy economics expert, who was not involved with the study, called the report a “very useful contribution” after a long period in which segments of the automotive industry argued there was too little information to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” the expert said. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and in the light of this data.”