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PHEVs produce almost five times more global warming pollution than official data show, according to a recent report.

Growing Discrepancy In Lab and Real-World Emissions

Data shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a non-profit group. That differs significantly with lab estimates, which suggested a 75% reduction in emissions.

Analysts studied data from in-vehicle energy use meters of 800,000 cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” said a senior analyst participating in the report. “This gap is growing and poses a significant issue. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles driven in electric mode relative to total mileage. They found that only a quarter of driving was completed in EV mode, while lab estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were significantly higher than official projections. This happened because electric motors were insufficiently powerful enough to function alone, resulting to combustion motors using gasoline for almost a third of the distance covered in electric mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV emissions enabled four major carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 extra annually in operating expenses than is estimated under lab tests.

“The bold statements that manufacturers like to make about their PHEV cars are clearly far from the truth,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the car sector and opposition from EU countries with significant car manufacturing.

Some high-level politicians have proposed PHEVs as a potential “flexibility” option to include in the legislation.

One external energy policy expert, who was not involved with the research, described the analysis a “very useful contribution” after years in which segments of the car industry claimed there was insufficient information to properly assess real-world CO2 output.

“The results show, without question, that the gap between lab and actual PHEV energy use and CO₂ output is much, much greater than for petrol or conventional vehicles,” they stated. “All regulatory changes regarding PHEVs should be implemented with utmost caution and considering this evidence.”