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

Growing Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy organization. This contrasts sharply with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers studied data from onboard energy use meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a lead analyst involved in the study. “That discrepancy is growing and poses a serious issue. As a result, PHEVs emit nearly as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric power compared to overall distance. They determined that just 27% of travel was completed in EV mode, whereas lab estimates assumed over four-fifths.

Even, when running in electric mode, pollution amounts were well above lab estimates. That happened because electric motors were not strong sufficient to operate independently, leading to engines using gasoline for almost one-third of the distance completed in EV mode.

Regulatory and Financial Implications

According to estimates, the underestimation of PHEV emissions allowed four large carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 more per year in operating costs than is estimated under laboratory tests.

“The bold claims that automakers like to make about their PHEV cars are obviously far from the truth,” stated a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn again into policy 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 heavy pressure from the car sector and resistance from EU countries with large automotive manufacturing.

Several high-level politicians have suggested PHEVs as a potential “compromise” solution to include in the legislation.

One independent energy policy expert, who was unaffiliated with the study, described the report a “very useful contribution” after a long period in which parts of the automotive sector argued there was too little data to properly assess real-world CO2 output.

“The results demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional cars,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and in the light of that data.”