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Plug-in hybrid cars produce almost five times more global warming pollution than lab-reported figures show, as per a new report.

Widening Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs release just one-fifth less CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit group. This contrasts significantly with lab tests, which suggested a 75% reduction in pollution.

Analysts examined data from in-vehicle energy use monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” stated a lead analyst participating in the study. “This gap is widening and creates a significant problem. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of miles driven in electric power relative to total mileage. The team found that just 27% of driving was completed in electric mode, while lab estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were significantly higher than lab projections. That occurred because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors using gasoline for almost a third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV emissions allowed several major carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ targets.

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

“The strong claims that automakers often promote about their PHEV cars are obviously way off the truth,” commented a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have lately been brought back into political discussions as carmakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large car manufacturing.

Some senior officials have suggested plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

An independent energy economics expert, who was unaffiliated with the study, described the analysis a “very useful addition” after a long period in which parts of the car industry argued there was too little data to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional cars,” they said. “All policy adjustments regarding PHEVs should be made with utmost care and in the light of this evidence.”