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Plug-in hybrid cars emit almost five times more global warming emissions than official data indicate, as per a recent analysis.

Growing Gap Between Official and Actual Emissions

Data reveals that PHEVs release only one-fifth less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy organization. This differs sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption meters of 800,000 cars registered in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” stated a senior analyst participating in the report. “That discrepancy is widening and poses a serious problem. As a result, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery mode compared to total mileage. They determined that just 27% of travel was done in EV mode, whereas official estimates suggested 84%.

Even, when running in electric mode, pollution amounts were significantly higher than official estimates. This occurred because EV motors were insufficiently powerful sufficient to function independently, leading to engines using fossil fuels for almost one-third of the distance completed in EV mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled several large carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 more annually in operating costs than would be assumed under lab conditions.

“The strong statements that manufacturers like to make about their PHEV vehicles are obviously way off the truth,” commented a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been drawn again into political debates as automakers have pressed the EU to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with large car industries.

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

One external energy policy specialist, who was not involved with the research, called the analysis a “highly valuable addition” after years in which parts of the car sector claimed there was too little information to properly assess real-world CO2 output.

“The results demonstrate, without question, that the difference between lab and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional cars,” they said. “Any policy adjustments regarding PHEVs should be implemented with extreme caution and in the light of that data.”