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

Widening Discrepancy In Official and Actual CO2 Output

Data shows that PHEVs release only 19% less CO₂ than conventional petrol and diesel vehicles, based on research conducted by a advocacy organization. That differs sharply with lab tests, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” stated a lead analyst involved in the report. “This discrepancy is growing and poses a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in electric mode compared to total distance. They found that just a quarter of travel was completed in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful sufficient to function independently, leading to combustion motors burning gasoline for almost one-third of the distance completed in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV emissions enabled several large automaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 extra per year in operating costs than would be estimated under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought again into political discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and opposition from EU countries with significant car manufacturing.

Several senior officials have suggested plug-in hybrids as a potential “flexibility” option to introduce in the legislation.

An external energy policy expert, who was unaffiliated with the study, called the report a “very useful addition” after years in which segments of the car sector argued there was insufficient information to accurately assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” the expert said. “All regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of that evidence.”