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Plug-in hybrid cars release nearly five times greater planet-heating emissions than lab-reported data show, as per a recent report.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs emit only one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a advocacy group. This contrasts sharply with laboratory estimates, which assumed a 75% decrease in emissions.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 cars registered in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” stated a lead analyst participating in the study. “This gap is growing and creates a significant problem. Consequently, PHEVs emit almost as much as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery mode compared to total mileage. They found that only a quarter of travel was completed in EV mode, while lab estimates assumed over four-fifths.

Additionally, when running in electric mode, emission amounts were well above official projections. That occurred because EV motors were not strong enough to operate independently, resulting to engines burning fossil fuels for nearly a third of the distance covered in EV mode.

Policy and Economic Consequences

According to estimates, the underestimation of PHEV emissions allowed several large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating costs than would be estimated under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV cars are obviously far from the truth,” commented a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into political discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant car manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One external energy economics specialist, who was unaffiliated with the research, described the report a “very useful addition” after a long period in which parts of the car industry claimed there was insufficient data to accurately assess actual emissions.

“The results demonstrate, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “All regulatory changes concerning PHEVs should be made with extreme caution and considering this data.”