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PHEVs release nearly five times more global warming pollution than lab-reported data indicate, as per a recent analysis.

Widening Gap Between Lab and Real-World Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional gas and diesel cars, according to analysis conducted by a non-profit organization. That contrasts significantly with laboratory estimates, which suggested a three-quarters reduction in emissions.

Researchers examined data from onboard fuel consumption monitors 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, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” stated a senior analyst involved in the report. “This gap is widening and creates a serious problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric mode relative to overall distance. They determined that just a quarter of travel was completed in electric mode, while lab estimates suggested 84%.

Additionally, when operating in electric mode, pollution amounts were significantly higher than official projections. That happened because EV motors were not strong enough to operate independently, resulting to combustion motors burning fossil fuels for nearly a third of the distance covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed four major automaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating expenses than is assumed under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into political discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant automotive industries.

Some senior officials have proposed PHEVs as a possible “compromise” solution to introduce in the regulation.

An external energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the automotive sector argued there was insufficient data to properly assess actual emissions.

“The results show, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel cars,” they stated. “All policy adjustments concerning PHEVs should be made with extreme caution and considering this evidence.”