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Plug-in hybrid cars produce almost five times more global warming emissions than official figures show, according to a recent analysis.

Widening Gap In Lab and Actual Emissions

Data shows that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit group. This contrasts significantly with laboratory tests, which assumed a three-quarters reduction in emissions.

Researchers studied data from onboard energy use meters of 800,000 cars sold in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are falling,” said a senior analyst involved in the report. “That discrepancy is widening and creates a significant problem. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Primary Reasons Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric power compared to overall mileage. They determined that only 27% of driving was completed in EV mode, while official estimates assumed over four-fifths.

Even, when running in EV mode, emission levels were well above lab projections. That occurred because EV motors were not strong sufficient to function independently, resulting to engines burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV emissions allowed several large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra annually in operating expenses than is estimated under laboratory conditions.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been drawn back into policy debates as carmakers have pressed the EU to weaken CO₂ standards. A proposed 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.

Several high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

An independent energy economics expert, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the automotive industry argued there was too little data to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional cars,” the expert stated. “All policy changes concerning PHEVs should be made with utmost caution and in the light of this data.”