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Plug-in hybrid electric vehicles release nearly five times greater planet-heating pollution than official figures indicate, as per a new analysis.

Growing Gap Between Official and Actual CO2 Output

Statistics reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy group. That differs sharply with lab estimates, which assumed a 75% reduction in emissions.

Researchers examined information from onboard energy use monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” stated a senior researcher participating in the study. “This gap is growing and poses a serious issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked most of the gap to overestimates of the “utility factor” – the percentage of miles driven in electric power relative to total distance. They found that just 27% of driving was completed in EV mode, while official estimates assumed over four-fifths.

Even, when running in electric mode, emission levels were well above lab projections. This happened because EV motors were not strong enough to operate independently, leading to combustion motors using fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several major automaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 more per year in operating costs than would be estimated under lab conditions.

“The strong statements that automakers often promote about their plug-in hybrid vehicles are clearly way off the truth,” stated a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been brought again into political debates as automakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large automotive industries.

Several high-level politicians have suggested PHEVs as a possible “compromise” option to include in the regulation.

An external energy policy specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was insufficient information to accurately assess real-world emissions.

“The results demonstrate, beyond any doubt, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert stated. “All policy changes concerning PHEVs should be implemented with extreme caution and considering that evidence.”