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Plug-in hybrid cars release almost five times greater planet-heating emissions than lab-reported data indicate, according to a recent analysis.

Widening Gap In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit only 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a advocacy organization. That contrasts significantly with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 cars registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” said a senior analyst involved in the study. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric mode compared to total distance. They found that just 27% of travel was done in electric mode, while lab assumptions suggested 84%.

Additionally, when running in EV mode, emission levels were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to operate independently, resulting to combustion motors using fossil fuels for almost a third of the distance covered in electric mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV CO2 output allowed several large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more per year in operating expenses than would be assumed under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn back into political debates as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from member states with significant automotive industries.

Several high-level officials have proposed PHEVs as a possible “compromise” option to include in the regulation.

An independent energy policy expert, who was unaffiliated with the study, called the report a “highly valuable addition” after a long period in which segments of the automotive sector argued there was too little data to properly evaluate real-world emissions.

“The results demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel vehicles,” the expert said. “All regulatory changes concerning PHEVs should be made with utmost care and considering this data.”