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Plug-in hybrid electric vehicles release nearly five times greater global warming emissions than official data indicate, as per a recent analysis.

Widening Discrepancy In Official and Actual CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than traditional petrol and diesel vehicles, according to research carried out by a advocacy organization. This contrasts significantly with lab tests, which assumed a 75% reduction in pollution.

Researchers examined information from onboard fuel consumption meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” said a lead researcher participating in the report. “This gap is widening and poses a significant issue. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric power relative to overall distance. They determined that just 27% of travel was completed in EV mode, while official assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were well above official estimates. This occurred because EV motors were not strong enough to operate independently, resulting to engines using gasoline for almost one-third of the travel completed in electric mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled several large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more per year in operating costs than would be estimated under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have lately been brought back into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from member states with significant car industries.

Some high-level politicians have suggested plug-in hybrids as a potential “flexibility” option to introduce in the regulation.

An independent energy policy specialist, who was not involved with the study, described the analysis a “very useful addition” after years in which parts of the automotive sector claimed there was too little information to accurately assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost caution and considering that evidence.”