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Plug-in hybrid electric vehicles emit nearly 5x more global warming emissions than lab-reported data indicate, as per a new report.

Growing Gap Between Lab and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit group. This differs significantly with laboratory estimates, which assumed a 75% reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of 800,000 vehicles sold in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while official figures are falling,” stated a lead researcher participating in the report. “This gap is widening and poses a serious issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power relative to total distance. The team determined that just 27% of travel was done in EV mode, while lab assumptions assumed over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than lab projections. This occurred because EV motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors burning fossil fuels for almost a third of the distance completed in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled several large carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend about €500 more annually in running costs than would be assumed under lab tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are clearly far from the mark,” commented a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Automotive Pressure

Hybrid cars have lately been drawn back into policy debates as automakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant car manufacturing.

Some senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

One independent energy policy expert, who was not involved with the study, described the report a “very useful addition” after a long period in which segments of the automotive industry argued there was insufficient information to accurately assess actual emissions.

“The results show, without question, that the difference between official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “Any policy adjustments concerning PHEVs should be made with utmost caution and in the light of that data.”