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Plug-in hybrid cars emit nearly 5x greater planet-heating pollution than official figures indicate, as per a recent analysis.

Widening Gap In Official and Actual CO2 Output

Data shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy group. That differs sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while official figures are falling,” stated a lead researcher participating in the report. “This gap is growing and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in electric mode relative to total distance. They found that just 27% of driving was completed in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab projections. That happened because EV motors were not strong sufficient to operate independently, resulting to combustion motors burning fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV emissions enabled several large automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 extra annually in running costs than would be assumed under laboratory conditions.

“The bold statements that automakers like to make about their PHEV vehicles are obviously way off the truth,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn again into political debates as carmakers have pressed the European Union to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from member states with large car industries.

Some high-level politicians have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One independent energy policy expert, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which segments of the car sector argued there was too little data to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” they stated. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of this evidence.”