🔗 Share this article

PHEVs produce nearly 5x more planet-heating emissions than lab-reported figures indicate, according to a recent report.

Growing Gap Between Lab and Actual Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit group. That contrasts sharply with lab tests, which assumed a three-quarters reduction in emissions.

Researchers examined data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a senior researcher involved in the report. “This gap is growing and creates a serious issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery mode relative to overall mileage. The team found that only 27% of driving was completed in EV mode, while lab assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above official projections. That occurred because EV motors were not strong sufficient to function alone, resulting to engines using fossil fuels for almost a third of the distance covered in EV mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV emissions enabled four large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more per year in running expenses than would be assumed under laboratory conditions.

“The bold statements that automakers often promote about their PHEV cars are obviously way off the mark,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into political discussions as carmakers have pressed the EU to weaken CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with large car industries.

Several high-level politicians have proposed plug-in hybrids as a potential “compromise” solution to include in the legislation.

One independent energy economics specialist, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was too little data to accurately assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” they said. “Any policy changes concerning PHEVs should be implemented with extreme care and in the light of this data.”