🔗 Share this article

Plug-in hybrid cars produce almost five times greater global warming emissions than official data indicate, according to a new analysis.

Growing Gap In Official and Real-World Emissions

Data shows that PHEVs release only 19% less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy group. That contrasts sharply with lab tests, which suggested a 75% decrease in pollution.

Researchers studied information from onboard energy use meters of 800,000 vehicles sold in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” stated a lead researcher involved in the study. “That gap is growing and creates a significant issue. As a result, PHEVs emit nearly as much as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers travelled in battery power relative to total distance. The team determined that only a quarter of driving was completed in EV mode, while official estimates assumed 84%.

Additionally, when running in electric mode, emission levels were well above lab projections. This happened because electric motors were insufficiently powerful enough to operate alone, leading to engines burning fossil fuels for nearly one-third of the travel covered in EV mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would spend about €500 extra annually in operating expenses than would be estimated under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into political debates as automakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car sector and resistance from EU countries with large car manufacturing.

Several high-level officials have suggested plug-in hybrids as a potential “compromise” option to include in the regulation.

One external energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable addition” after years in which parts of the automotive sector argued there was insufficient information to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional cars,” the expert said. “Any regulatory changes concerning PHEVs should be implemented with extreme care and considering that data.”