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PHEVs release nearly 5x greater planet-heating pollution than lab-reported figures show, according to a recent analysis.

Widening Gap Between Lab and Actual Emissions

Statistics shows that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel cars, based on research carried out by a non-profit organization. That contrasts sharply with lab estimates, which assumed a 75% decrease in pollution.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand vehicles sold in the EU 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 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a senior researcher participating in the report. “This discrepancy is growing and poses a significant issue. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in battery power relative to total distance. They determined that just 27% of travel was done in EV mode, whereas lab estimates suggested 84%.

Even, when running in EV mode, emission amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful enough to operate independently, leading to engines burning gasoline for almost a third of the travel completed in EV mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV emissions enabled several large automaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in operating costs than is estimated under laboratory conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the mark,” stated a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into political discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and resistance from EU countries with significant car manufacturing.

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

One external energy economics specialist, who was not involved with the study, called the report a “highly valuable addition” after a long period in which segments of the car sector claimed there was too little information to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap between lab and actual PHEV energy use and CO₂ output is significantly larger than for petrol or diesel vehicles,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and in the light of that data.”