🔗 Share this article

Plug-in hybrid cars emit nearly five times greater planet-heating pollution than lab-reported data show, according to a new analysis.

Growing Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit group. That differs significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are falling,” said a senior analyst involved in the report. “This discrepancy is widening and creates a serious problem. Consequently, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery power compared to overall distance. They determined that only a quarter of travel was done in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when running in EV mode, pollution amounts were significantly higher than official projections. That occurred because EV motors were not strong enough to function independently, resulting to combustion motors using fossil fuels for nearly a third of the travel covered in EV mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed several major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 extra per year in running expenses than would be assumed under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly way off the mark,” commented a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced heavy pressure from the automotive industry and opposition from member states with significant car manufacturing.

Some high-level politicians have proposed PHEVs as a possible “flexibility” option to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the study, called the report a “very useful addition” after a long period in which segments of the car sector argued there was too little data to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they stated. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of this evidence.”