🔗 Share this article

Plug-in hybrid electric vehicles emit almost five times greater planet-heating pollution than lab-reported figures indicate, according to a new analysis.

Growing Gap Between Official and Real-World Emissions

Data shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a advocacy organization. That contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined information from onboard energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a senior researcher involved in the study. “This gap is widening and poses a serious issue. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Analysts linked most of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to total distance. They determined that just a quarter of driving was completed in EV mode, whereas official assumptions suggested 84%.

Additionally, when running in electric mode, emission levels were significantly higher than lab projections. This happened because electric motors were insufficiently powerful sufficient to function alone, leading to engines burning gasoline for nearly one-third of the distance covered in electric mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled four large automaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 extra annually in running expenses than would be assumed under lab conditions.

“The bold statements that automakers often promote about their PHEV vehicles are clearly way off the mark,” stated a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little better than standard gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been drawn again into political debates as automakers have pressed the EU to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant car industries.

Several senior politicians have suggested PHEVs as a possible “compromise” option to introduce in the legislation.

An independent energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after a long period in which parts of the car industry claimed there was too little information to properly assess real-world emissions.

“These findings show, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost care and in the light of that data.”