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Plug-in hybrid cars emit nearly 5x more planet-heating pollution than official data show, as per a recent report.

Growing Discrepancy In Lab and Actual Emissions

Data shows that PHEVs release only 19% lower CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy group. That contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a lead analyst involved in the study. “That gap is widening and poses a significant issue. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in battery power compared to total mileage. The team found that just a quarter of driving was done in EV mode, whereas lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were well above lab projections. That happened because EV motors were not strong enough to operate alone, resulting to combustion motors using fossil fuels for almost a third of the distance covered in electric mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled four large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 extra annually in running costs than is assumed under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” commented a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been drawn again into political discussions as automakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the car sector and opposition from member states with significant automotive manufacturing.

Several senior politicians have suggested PHEVs as a potential “flexibility” option to include in the regulation.

One external energy policy expert, who was unaffiliated with the study, described the report a “very useful contribution” after years in which segments of the automotive industry argued there was insufficient information to accurately assess real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional vehicles,” they stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme caution and considering that data.”