🔗 Share this article

Plug-in hybrid electric vehicles produce almost five times greater planet-heating emissions than official figures show, according to a recent report.

Widening Discrepancy Between Official and Actual Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, according to analysis carried out by a non-profit group. This contrasts significantly with lab tests, which assumed a 75% decrease in pollution.

Analysts studied information from onboard energy use monitors of 800,000 vehicles sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” said a senior researcher participating in the report. “This gap is widening and creates a serious issue. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric power relative to total distance. The team determined that only 27% of travel was completed in EV mode, whereas lab assumptions assumed over four-fifths.

Even, when operating in electric mode, emission amounts were well above official projections. This happened because EV motors were insufficiently powerful enough to function alone, leading to engines using gasoline for almost a third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled several major carmaker groups to avoid over €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 more per year in operating expenses than would be assumed under lab conditions.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the truth,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought back into political discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with significant car industries.

Some senior officials have proposed plug-in hybrids as a possible “compromise” solution to include in the regulation.

One independent energy policy expert, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which parts of the automotive sector argued there was insufficient data to accurately assess real-world CO2 output.

“The results show, without question, that the gap in lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they said. “Any regulatory changes regarding PHEVs should be made with utmost caution and considering that evidence.”