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PHEVs emit nearly five times greater planet-heating pollution than official figures show, as per a new report.

Growing Gap Between Lab and Actual CO2 Output

Data reveals that PHEVs release only 19% lower CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a advocacy organization. This differs significantly with lab estimates, which suggested a 75% reduction in emissions.

Researchers examined information from onboard fuel consumption monitors of 800,000 cars registered in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” stated a lead researcher involved in the study. “This gap is widening and creates a significant problem. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power compared to overall distance. They determined that only 27% of driving was done in electric mode, while lab assumptions assumed over four-fifths.

Additionally, when running in EV mode, pollution amounts were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to function independently, resulting to combustion motors burning fossil fuels for nearly one-third of the travel covered in EV mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV CO2 output allowed four large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra annually in running costs than would be estimated under laboratory tests.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are obviously way off the truth,” commented a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have recently been brought again into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with significant automotive industries.

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

One external energy policy specialist, who was unaffiliated with the study, called the report a “highly valuable contribution” after a long period in which segments of the car industry claimed there was too little information to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert said. “Any policy adjustments regarding PHEVs should be made with utmost care and in the light of that evidence.”