Plug in Hybrid Vehicles Pollute Almost as Heavily as Gasoline Vehicles, Study Finds

Plug-in hybrid cars emit nearly 5x more planet-heating emissions than official figures show, as per a new report.

Widening Discrepancy In Official and Actual Emissions

Data shows that PHEVs release just 19% less CO₂ than conventional gas and diesel cars, based on research conducted by a advocacy group. That differs significantly with laboratory estimates, which assumed a three-quarters decrease in emissions.

Researchers examined information from onboard fuel consumption meters of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” said a senior analyst participating in the report. “This discrepancy is growing and creates a serious issue. As a result, PHEVs emit almost as much as petrol cars.”

Key Reasons Driving the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery mode compared to overall mileage. They found that only a quarter of driving was completed in EV mode, whereas lab estimates assumed 84%.

Even, when operating in electric mode, pollution amounts were significantly higher than official projections. This happened because EV motors were insufficiently powerful enough to function independently, resulting to engines using gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 more annually in operating costs than is assumed under laboratory conditions.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little better than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy debates as automakers have lobbied the EU to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “flexibility” solution to include in the legislation.

An independent energy economics specialist, who was unaffiliated with the research, described the analysis a “very useful contribution” after years in which parts of the car sector argued there was too little data to properly evaluate real-world emissions.

“These findings demonstrate, without question, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” they said. “Any policy changes regarding PHEVs should be made with extreme care and considering this evidence.”