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PHEVs emit nearly five times greater global warming pollution than official figures indicate, according to a new report.

Growing Gap Between Lab and Actual CO2 Output

Data reveals that PHEVs release just 19% less CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy group. This differs significantly with lab tests, which suggested a three-quarters decrease in pollution.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” said a senior researcher involved in the report. “This gap is growing and creates a significant problem. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in battery mode compared to total distance. They determined that only 27% of travel was completed in EV mode, whereas lab estimates assumed over four-fifths.

Even, when running in EV mode, pollution amounts were significantly higher than lab projections. That happened because EV motors were not strong enough to function alone, resulting to combustion motors burning fossil fuels for almost a third of the distance completed in electric mode.

Regulatory and Financial Implications

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

Additionally, drivers of PHEVs would spend about €500 extra annually in running costs than would be estimated under lab conditions.

“The strong statements that manufacturers like to make about their PHEV cars are clearly far from the mark,” stated a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn again into political discussions as automakers have pressed the European Union to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant car manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “compromise” option to include in the legislation.

One external energy economics expert, who was not involved with the study, called the analysis a “very useful contribution” after years in which parts of the automotive industry claimed there was insufficient information to properly evaluate real-world emissions.

“These findings demonstrate, 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 said. “Any regulatory changes regarding PHEVs should be implemented with utmost care and considering this evidence.”