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PHEVs produce almost five times more global warming pollution than official data show, according to a new analysis.

Growing Discrepancy Between Official and Actual Emissions

Data reveals that PHEVs emit only 19% less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit group. That contrasts significantly with lab estimates, which assumed a 75% reduction in emissions.

Researchers examined information from onboard energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” stated a senior researcher involved in the report. “This discrepancy is widening and creates a significant problem. As a result, PHEVs emit almost as heavily as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to overall mileage. They determined that just 27% of travel was completed in EV mode, while official assumptions suggested 84%.

Additionally, when running in electric mode, emission levels were well above lab projections. This occurred because EV motors were not strong sufficient to function independently, resulting to combustion motors using fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output enabled several large carmaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 extra annually in operating costs than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are obviously far from the truth,” commented a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been brought again into political debates as automakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with significant automotive industries.

Several high-level politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

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 sector claimed there was too little data to properly evaluate actual emissions.

“These findings show, 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,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with utmost care and considering that data.”