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Plug-in hybrid electric vehicles produce nearly 5x greater planet-heating pollution than lab-reported data show, as per a recent report.

Widening Discrepancy Between Lab and Actual Emissions

Data reveals that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a advocacy group. That contrasts significantly with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers studied data from onboard fuel consumption meters of 800,000 cars registered in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a lead researcher involved in the report. “This gap is widening and creates a serious issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Driving the Discrepancy

Analysts linked most of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric power relative to total distance. They found that only a quarter of travel was done in EV mode, whereas official estimates suggested 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than lab estimates. This happened because electric motors were not strong sufficient to operate alone, resulting to combustion motors burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV emissions enabled four large automaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more per year in operating expenses than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into political debates as carmakers have pressed the EU to relax CO₂ standards. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant car manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

An external energy economics expert, who was not involved with the research, described the report a “very useful addition” after a long period in which parts of the automotive industry claimed there was too little data to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional vehicles,” the expert said. “Any policy changes concerning PHEVs should be implemented with extreme care and in the light of this evidence.”