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PHEVs produce almost five times more global warming emissions than official data indicate, as per a new report.

Growing Gap In Lab and Real-World CO2 Output

Statistics shows that PHEVs release just 19% less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a non-profit group. That contrasts significantly with laboratory estimates, which assumed a three-quarters decrease in emissions.

Researchers studied data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” said a lead analyst involved in the study. “That gap is growing and poses a serious problem. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Reasons Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles travelled in battery mode compared to total distance. The team found that only a quarter of driving was completed in EV mode, while official estimates assumed over four-fifths.

Even, when operating in EV mode, emission levels were well above lab projections. That occurred because EV motors were not strong enough to function independently, resulting to engines burning gasoline for nearly a third of the distance covered in EV mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV emissions allowed four major automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 more per year in operating costs than is assumed under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” stated a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Pressure

Hybrid cars have recently been brought again into policy discussions as carmakers have pressed the European Union to weaken 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 EU countries with large car industries.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the legislation.

An external energy economics expert, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which segments of the car sector claimed there was too little information to accurately evaluate real-world emissions.

“The results show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel cars,” the expert said. “Any policy adjustments concerning PHEVs should be implemented with utmost care and considering that data.”