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PHEVs produce almost five times greater planet-heating emissions than lab-reported data show, as per a new report.

Growing Discrepancy In Lab and Actual Emissions

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel cars, according to analysis conducted by a advocacy organization. That contrasts significantly with laboratory estimates, which assumed a three-quarters reduction in pollution.

Analysts studied data from in-vehicle fuel consumption meters of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” said a senior analyst involved in the study. “This discrepancy is widening and creates a significant issue. As a result, PHEVs emit almost as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in electric power compared to total distance. They determined that only 27% of driving was completed in electric mode, while lab estimates assumed 84%.

Even, when operating in EV mode, emission amounts were significantly higher than official projections. That happened because electric motors were insufficiently powerful sufficient to operate independently, leading to engines burning fossil fuels for almost one-third of the distance covered in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled four major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 extra annually in running costs than is assumed under lab tests.

“The bold claims that manufacturers often promote about their PHEV cars are clearly way off the truth,” commented a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have recently been brought back into political discussions as carmakers have lobbied the EU to weaken CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from member states with significant automotive manufacturing.

Several high-level politicians have proposed PHEVs as a potential “flexibility” solution to introduce in the legislation.

One independent energy policy expert, who was not involved with the research, called the analysis a “very useful contribution” after years in which segments of the automotive industry claimed there was insufficient information to accurately assess actual CO2 output.

“These findings show, without question, that the difference between official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and considering that data.”