🔗 Share this article

Plug-in hybrid cars release nearly 5x greater planet-heating emissions than official data indicate, as per a new report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs emit only 19% less CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy organization. That differs sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Researchers examined data from onboard fuel consumption monitors of eight hundred thousand cars sold in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” said a senior analyst participating in the study. “That discrepancy is widening and poses a significant issue. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of miles travelled in battery mode compared to total distance. They determined that only a quarter of travel was completed in EV mode, while official estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above official estimates. That happened because electric motors were not strong enough to operate alone, leading to engines using gasoline for almost one-third of the distance completed in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled several major automaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 extra annually in running costs than is estimated under lab tests.

“The bold statements that manufacturers like to make about their PHEV cars are clearly far from the mark,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been brought again into political debates as automakers have lobbied the EU to weaken CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with significant car manufacturing.

Several senior officials have suggested plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the study, called the analysis a “highly valuable addition” after a long period in which parts of the car industry claimed there was insufficient data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they stated. “Any policy changes regarding PHEVs should be made with utmost care and in the light of this data.”