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Plug-in hybrid electric vehicles produce almost five times more planet-heating pollution than official data indicate, as per a recent analysis.

Widening Gap In Lab and Real-World CO2 Output

Data shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, according to research conducted by a non-profit group. That contrasts sharply with laboratory tests, which assumed a three-quarters reduction in pollution.

Analysts studied information from in-vehicle energy use monitors of 800,000 vehicles registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a lead analyst participating in the report. “That discrepancy is widening and poses a serious problem. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery power relative to overall mileage. They determined that only 27% of travel was completed in electric mode, whereas official estimates suggested over four-fifths.

Even, when running in EV mode, pollution levels were well above lab estimates. That occurred because EV motors were not strong enough to operate alone, resulting to engines burning gasoline for almost a third of the distance completed in EV mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV emissions allowed four large carmaker companies to avoid over €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more annually in operating expenses than would be estimated under lab conditions.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously far from the truth,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little better than standard gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been drawn again into policy debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and resistance from member states with large automotive industries.

Some high-level politicians have proposed plug-in hybrids as a possible “compromise” solution to include in the legislation.

An independent energy economics expert, who was not involved with the research, called the report a “very useful addition” after a long period in which segments of the car industry claimed there was too little data to accurately evaluate real-world emissions.

“The results show, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional cars,” the expert said. “All regulatory changes regarding PHEVs should be implemented with extreme caution and in the light of this evidence.”