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Plug-in hybrid electric vehicles release almost 5x more planet-heating emissions than lab-reported data show, as per a recent analysis.

Growing Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel vehicles, based on research conducted by a non-profit group. This contrasts significantly with lab estimates, which suggested a 75% reduction in pollution.

Analysts studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” said a senior analyst involved in the study. “That gap is growing and poses a significant problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Driving the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery power compared to overall distance. They found that just a quarter of driving was done in electric mode, whereas lab assumptions suggested 84%.

Additionally, when running in electric mode, emission amounts were well above lab estimates. That occurred because electric motors were not strong sufficient to operate independently, resulting to combustion motors burning fossil fuels for almost a third of the distance completed in EV mode.

Regulatory and Economic Implications

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

Additionally, owners of PHEVs would spend approximately €500 more annually in running costs than is assumed under lab tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are clearly far from the mark,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been brought back into policy debates as carmakers have pressed the EU to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced intense lobbying from the car sector and opposition from EU countries with significant car industries.

Some senior politicians have suggested PHEVs as a possible “compromise” option to include in the legislation.

One external energy economics specialist, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which segments of the automotive sector claimed there was too little data to properly assess real-world emissions.

“The results demonstrate, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel cars,” the expert said. “All regulatory changes concerning PHEVs should be made with utmost care and considering that data.”