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Plug-in hybrid cars emit almost five times greater global warming emissions than official figures indicate, as per a recent analysis.

Widening Gap In Lab and Real-World Emissions

Data reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy group. That differs sharply with laboratory estimates, which suggested a three-quarters decrease in pollution.

Analysts studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while official figures are falling,” said a lead analyst participating in the report. “This discrepancy is growing and creates a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in battery power relative to total mileage. They determined that just 27% of travel was completed in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were well above lab estimates. That occurred because electric motors were not strong enough to function alone, leading to combustion motors burning fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

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

“The strong statements that manufacturers like to make about their PHEV cars are obviously way off the truth,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been brought back into political discussions as carmakers have pressed the European Union to relax CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant automotive industries.

Some senior officials have suggested plug-in hybrids as a possible “compromise” option to include in the legislation.

An independent energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which parts of the automotive industry claimed there was too little information to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert stated. “Any regulatory adjustments concerning PHEVs should be made with extreme caution and considering that data.”