🔗 Share this article

Plug-in hybrid cars emit nearly five times greater global warming pollution than lab-reported data indicate, according to a new analysis.

Widening Gap Between Lab and Actual Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a advocacy organization. That contrasts significantly with laboratory tests, which suggested a 75% decrease in emissions.

Analysts studied information from onboard fuel consumption meters of eight hundred thousand cars sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a lead researcher involved in the study. “That gap is widening and poses a serious problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power compared to total mileage. They found that only 27% of travel was done in electric mode, while lab assumptions assumed 84%.

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

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV emissions enabled several large carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in running expenses than is estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV cars are obviously far from the truth,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have lately been drawn again into political debates as automakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with significant automotive industries.

Several senior politicians have proposed plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

An independent energy economics expert, who was unaffiliated with the study, called the report a “highly valuable addition” after years in which parts of the car sector argued there was insufficient information to accurately assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert stated. “Any policy changes concerning PHEVs should be made with utmost care and considering this data.”