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

Growing Discrepancy In Official and Actual CO2 Output

Statistics shows that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a advocacy organization. This differs significantly with lab tests, which suggested a 75% decrease in pollution.

Researchers examined information from onboard energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “That discrepancy is growing and poses a significant issue. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode compared to overall distance. The team determined that only a quarter of travel was completed in electric mode, while lab assumptions suggested over four-fifths.

Additionally, when operating in EV mode, pollution levels were significantly higher than lab projections. That occurred because EV motors were not strong enough to function independently, resulting to combustion motors burning gasoline for nearly a third of the distance completed in EV mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed several major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra annually in running costs than is estimated under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been drawn again into political debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with large automotive manufacturing.

Several high-level officials have suggested plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

An external energy economics specialist, who was not involved with the study, called the report a “very useful addition” after a long period in which parts of the car sector claimed there was too little information to accurately assess actual emissions.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert said. “All policy changes regarding PHEVs should be implemented with extreme care and in the light of this data.”