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Plug-in hybrid cars produce nearly five times greater global warming emissions than lab-reported figures indicate, according to a recent report.

Growing Discrepancy In Lab and Real-World Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy group. This differs significantly with laboratory estimates, which assumed a 75% decrease in emissions.

Analysts studied information from in-vehicle energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” said a senior analyst participating in the report. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs emit almost as much as petrol cars.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric mode compared to overall distance. They found that only a quarter of driving was completed in EV mode, while official estimates suggested over four-fifths.

Even, when operating in electric mode, pollution levels were significantly higher than lab projections. That happened because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning gasoline for nearly a third of the distance completed in electric mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 extra annually in operating expenses than would be assumed under lab conditions.

“The strong claims that automakers like to make about their PHEV cars are clearly far from the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant automotive industries.

Some senior politicians have suggested PHEVs as a possible “compromise” solution to introduce in the regulation.

An external energy economics specialist, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert said. “Any policy changes regarding PHEVs should be implemented with utmost caution and considering that data.”