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PHEVs release almost five times more global warming pollution than official figures show, as per a recent report.

Widening Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a non-profit organization. This contrasts significantly with laboratory tests, which assumed a three-quarters reduction in pollution.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” said a senior researcher involved in the report. “That gap is growing and creates a serious problem. As a result, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in battery mode compared to overall distance. The team determined that just a quarter of driving was done in EV mode, while lab estimates assumed over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than lab projections. That happened because electric motors were not strong enough to operate independently, leading to combustion motors using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV emissions allowed four large automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in operating expenses than is estimated under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have lately been brought back into political discussions as carmakers have pressed the EU to weaken CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large car industries.

Several senior officials have suggested plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the research, described the analysis a “very useful addition” after years in which segments of the automotive industry argued there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert said. “Any policy adjustments regarding PHEVs should be made with extreme caution and in the light of that evidence.”