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Plug-in hybrid electric vehicles emit almost 5x more global warming pollution than lab-reported data show, according to a new report.

Widening Discrepancy In Official and Actual Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel vehicles, according to research carried out by a advocacy organization. That differs significantly with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand cars registered in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a senior researcher participating in the study. “This discrepancy is growing and creates a serious issue. As a result, PHEVs pollute almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery mode relative to total mileage. The team found that only a quarter of travel was completed in electric mode, while lab estimates suggested over four-fifths.

Even, when operating in electric mode, emission amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful sufficient to function independently, resulting to engines burning gasoline for nearly a third of the distance completed in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed several large automaker groups to avoid more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 more per year in operating costs than is estimated under lab tests.

“The bold statements that manufacturers often promote about their PHEV cars are clearly far from the truth,” commented a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Political Debate and Industry Lobbying

Hybrid cars have lately been brought back into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and resistance from EU countries with large automotive industries.

Some senior officials have suggested PHEVs as a possible “flexibility” option to include in the regulation.

One independent energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful addition” after years in which segments of the car industry claimed there was insufficient information to properly evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost care and considering that evidence.”