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PHEVs emit nearly 5x greater global warming emissions than lab-reported figures indicate, according to a new report.

Growing Discrepancy Between Official and Actual CO2 Output

Data reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. This differs sharply with lab estimates, which suggested a three-quarters decrease in pollution.

Analysts studied information from in-vehicle energy use meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” said a senior analyst involved in the report. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in electric power compared to total distance. They found that only 27% of driving was done in EV mode, while lab estimates assumed over four-fifths.

Even, when running in electric mode, pollution levels were well above lab estimates. This occurred because EV motors were not strong enough to operate alone, leading to combustion motors using gasoline for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed several large carmaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 more annually in running expenses than would be estimated under laboratory tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are obviously way off the truth,” stated a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have lately been drawn back into political debates as automakers have lobbied the European Union to relax CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with large automotive manufacturing.

Some high-level politicians have suggested PHEVs as a possible “flexibility” solution to include in the legislation.

One external energy policy specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which parts of the car industry argued there was too little data to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional cars,” they stated. “Any regulatory adjustments concerning PHEVs should be made with utmost caution and in the light of that data.”