Plug in Hybrid Cars Pollute Almost as Much as Gasoline Vehicles, Report Finds

Plug-in hybrid electric vehicles produce nearly 5x more planet-heating emissions than official data show, according to a new analysis.

Widening Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit group. That differs significantly with lab tests, which assumed a three-quarters decrease in pollution.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand cars registered in the EU between 2021 and 2023. They 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 senior analyst participating in the study. “This gap is widening and poses a significant issue. As a result, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric power relative to overall distance. The team found that only 27% of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, emission amounts were significantly higher than lab estimates. This happened because EV motors were not strong enough to operate alone, leading to engines using gasoline for nearly one-third of the travel covered in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions allowed four large automaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend about €500 more annually in operating costs than would be estimated under lab conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” commented a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Hybrid cars have recently been brought back into policy debates as carmakers have pressed the EU to weaken CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant automotive industries.

Some senior politicians have proposed plug-in hybrids as a potential “compromise” option to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which parts of the automotive industry claimed there was insufficient information to properly assess actual emissions.

“The results show, without question, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with extreme care and considering this data.”