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Plug-in hybrid electric vehicles release nearly five times greater planet-heating emissions than official data indicate, as per a new report.

Growing Gap In Lab and Actual Emissions

Statistics shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, according to research carried out by a non-profit organization. This contrasts sharply with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts examined data from onboard fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” stated a senior researcher involved in the report. “That discrepancy is growing and poses a serious problem. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric power relative to overall distance. They found that just 27% of driving was done in EV mode, whereas official estimates assumed 84%.

Even, when running in EV mode, emission amounts were well above official projections. This occurred because EV motors were insufficiently powerful enough to function alone, resulting to engines burning gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV emissions allowed four large automaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 extra per year in operating costs than is assumed under lab tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” stated a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy debates as automakers have lobbied the EU to relax CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car industry and resistance from EU countries with large car industries.

Several high-level politicians have suggested PHEVs as a potential “flexibility” solution to introduce in the regulation.

One independent energy policy specialist, who was not involved with the research, described the report a “very useful addition” after years in which parts of the car industry claimed there was too little data to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and in the light of this evidence.”