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Plug-in hybrid electric vehicles emit almost 5x more planet-heating pollution than lab-reported figures indicate, as per a recent report.

Widening Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to research carried out by a advocacy group. That differs significantly with laboratory estimates, which suggested a 75% decrease in emissions.

Analysts examined data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” said a lead researcher participating in the study. “This discrepancy is growing and poses a significant issue. As a result, PHEVs pollute nearly as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in electric power compared to overall mileage. They determined that only 27% of driving was done in electric mode, while official assumptions assumed over four-fifths.

Even, when running in EV mode, emission amounts were significantly higher than official estimates. This happened because electric motors were insufficiently powerful enough to operate alone, resulting to engines using fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled several large carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra annually in running costs than is estimated under lab tests.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been brought again into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the car industry and resistance from member states with significant automotive manufacturing.

Some senior politicians have suggested PHEVs as a potential “flexibility” option to include in the legislation.

An independent energy economics specialist, who was unaffiliated with the study, called the report a “very useful addition” after years in which parts of the car industry argued there was too little information to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel cars,” the expert said. “Any policy adjustments concerning PHEVs should be implemented with utmost care and in the light of that data.”