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Plug-in hybrid cars produce almost five times more planet-heating emissions than official data show, as per a recent report.

Widening Discrepancy In Official and Actual CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a non-profit group. That contrasts sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied information from in-vehicle energy use monitors of 800,000 vehicles registered in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” said a lead researcher involved in the study. “That gap is widening and poses a serious issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power compared to overall mileage. The team found that only a quarter of driving was done in EV mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, pollution levels were well above lab estimates. That happened because EV motors were not strong sufficient to operate independently, leading to engines burning gasoline for almost a third of the distance covered in EV mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV emissions enabled four major carmaker companies to escape over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 more annually in running expenses than is estimated under lab conditions.

“The strong statements that automakers like to make about their PHEV vehicles are clearly far from the mark,” commented a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have lately been brought again into policy discussions as carmakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with large car manufacturing.

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

An external energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable addition” after a long period in which parts of the automotive industry claimed there was too little information to properly assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme caution and in the light of this data.”