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Plug-in hybrid electric vehicles release almost five times greater global warming emissions than official figures show, as per a recent analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Data reveals that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, based on research conducted by a advocacy group. That contrasts significantly with lab estimates, which suggested a 75% reduction in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” stated a lead analyst participating in the study. “This gap is widening and creates a serious problem. As a result, PHEVs pollute almost as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery power compared to total distance. They determined that only 27% of travel was completed in EV mode, while official estimates assumed over four-fifths.

Even, when running in EV mode, emission levels were well above lab estimates. This happened because EV motors were insufficiently powerful enough to function independently, resulting to combustion motors using gasoline for nearly a third of the travel covered in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions allowed several major carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

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

“The strong claims that automakers often promote about their PHEV vehicles are clearly way off the mark,” stated a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been brought back into policy discussions as automakers have pressed the EU to relax CO₂ standards. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and opposition from member states with large automotive manufacturing.

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

An independent energy economics specialist, who was not involved with the research, described the report a “very useful contribution” after a long period in which segments of the automotive industry claimed there was insufficient data to accurately assess real-world emissions.

“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” they said. “All regulatory adjustments regarding PHEVs should be made with utmost care and considering this data.”