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Plug-in hybrid cars emit almost five times more planet-heating emissions than official figures show, according to a new analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Data shows that PHEVs release just 19% lower CO₂ than traditional petrol and diesel cars, according to analysis conducted by a advocacy organization. This contrasts significantly with lab estimates, which suggested a 75% decrease in pollution.

Analysts examined information from in-vehicle energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” said a lead researcher participating in the report. “This gap is widening and creates a significant problem. Consequently, PHEVs pollute almost as much as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to total mileage. The team determined that only a quarter of travel was completed in electric mode, whereas official assumptions suggested 84%.

Even, when operating in EV mode, pollution levels were well above official projections. That happened because EV motors were insufficiently powerful enough to function independently, leading to engines using fossil fuels for almost a third of the distance covered in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed four major automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 extra annually in operating expenses than would be assumed under laboratory conditions.

“The strong claims that automakers like to make about their PHEV cars are clearly far from the mark,” stated a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into political discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant automotive industries.

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

One external energy policy expert, who was unaffiliated with the research, described the analysis a “very useful contribution” after a long period in which segments of the car sector argued there was insufficient data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” the expert said. “Any regulatory changes concerning PHEVs should be implemented with extreme care and in the light of this evidence.”