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Plug-in hybrid cars emit nearly 5x more planet-heating pollution than official figures show, according to a recent analysis.

Widening Discrepancy In Official and Actual Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, according to research carried out by a non-profit group. This differs significantly with laboratory estimates, which assumed a 75% decrease in emissions.

Researchers studied information from in-vehicle energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a lead researcher participating in the study. “That discrepancy is growing and creates a serious issue. As a result, PHEVs pollute almost as much as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in battery mode compared to overall mileage. The team found that just a quarter of travel was done in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than official estimates. That happened because electric motors were not strong sufficient to function independently, leading to engines burning fossil fuels for nearly a third of the travel covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions allowed several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more annually in running expenses than is estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are clearly far from the truth,” stated a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been drawn again into policy debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant car manufacturing.

Some senior politicians have proposed PHEVs as a possible “compromise” option to include in the regulation.

An independent energy policy specialist, who was unaffiliated with the research, called the report a “very useful addition” after years in which segments of the automotive sector argued there was too little data to properly assess actual CO2 output.

“These findings show, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert stated. “All policy changes concerning PHEVs should be implemented with utmost caution and in the light of that evidence.”