Plug-in Hybrid electric Cars Pollute Almost as Much as Petrol Cars, Study Finds

Plug-in hybrid electric vehicles emit nearly five times more planet-heating emissions than official figures show, as per a recent report.

Widening Gap In Lab and Real-World Emissions

Data reveals that PHEVs release only 19% lower CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. That contrasts significantly with lab tests, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “This gap is widening and poses a serious problem. As a result, PHEVs pollute almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode relative to overall distance. They found that only a quarter of travel was completed in EV mode, whereas official estimates suggested 84%.

Even, when running in electric mode, pollution levels were significantly higher than lab estimates. This happened because EV motors were not strong enough to function alone, resulting to combustion motors using gasoline for nearly a third of the distance completed in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV emissions allowed four major automaker groups to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 extra per year in operating costs than is assumed under lab tests.

“The strong statements that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn again into political discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant automotive manufacturing.

Some senior politicians have proposed plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One independent energy policy expert, who was not involved with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the car industry argued there was too little data to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel vehicles,” they said. “All policy changes concerning PHEVs should be implemented with utmost caution and considering this evidence.”