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Plug-in hybrid electric vehicles emit almost five times more planet-heating pollution than official data show, according to a recent report.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a advocacy group. That contrasts significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” stated a lead analyst involved in the report. “That gap is widening and poses a significant issue. Consequently, PHEVs emit nearly as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric power relative to overall distance. The team found that just 27% of travel was completed in EV mode, while lab estimates suggested 84%.

Even, when running in EV mode, emission levels were well above lab projections. This occurred because electric motors were not strong sufficient to function alone, leading to combustion motors burning fossil fuels for nearly a third of the travel completed in electric mode.

Policy and Financial Implications

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

Additionally, owners of PHEVs would pay approximately €500 more per year in operating costs than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with large automotive industries.

Some high-level officials have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, called the report a “very useful addition” after a long period in which parts of the car sector claimed there was too little data to properly assess real-world emissions.

“The results show, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be made with utmost care and in the light of this data.”