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PHEVs produce almost 5x greater planet-heating emissions than lab-reported figures show, according to a recent report.

Widening Discrepancy Between Official and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a advocacy organization. That differs significantly with laboratory estimates, which suggested a three-quarters reduction in emissions.

Analysts studied information from onboard fuel consumption meters of 800,000 cars registered in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead researcher participating in the report. “This gap is growing and poses a significant problem. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total mileage. The team found that only 27% of driving was completed in electric mode, whereas official assumptions assumed 84%.

Additionally, when operating in electric mode, pollution levels were well above official estimates. That happened because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors using fossil fuels for almost a third of the travel completed in electric mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV CO2 output allowed four major carmaker companies to escape over €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more per year in running costs than is assumed under laboratory conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Lobbying

Hybrid cars have recently been drawn again into political discussions as carmakers have pressed the EU to weaken CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car manufacturing.

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

One external energy economics specialist, who was not involved with the research, called the report a “very useful contribution” after a long period in which segments of the automotive industry claimed there was insufficient data to properly evaluate real-world emissions.

“The results demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and considering that data.”