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Plug-in hybrid electric vehicles produce almost 5x more planet-heating emissions than lab-reported data show, according to a recent analysis.

Growing Gap In Official and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a advocacy organization. This differs significantly with lab tests, which suggested a three-quarters reduction in pollution.

Researchers studied data from onboard energy use monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” said a lead analyst participating in the report. “That gap is widening and creates a serious issue. Consequently, PHEVs emit almost as much as petrol vehicles.”

Key Factors Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to overall distance. The team determined that only 27% of driving was done in EV mode, while lab estimates suggested over four-fifths.

Even, when running in electric mode, pollution levels were well above lab estimates. This occurred because electric motors were not strong enough to operate alone, resulting to combustion motors using gasoline for nearly a third of the travel covered in electric mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled four large carmaker companies to escape more than €5bn in fines between 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 more per year in operating expenses than would be assumed under lab tests.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Pressure

Hybrid cars have lately been drawn back into policy discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with significant automotive manufacturing.

Some senior officials have suggested plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, described the analysis a “very useful addition” after a long period in which segments of the automotive sector argued there was too little data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” the expert said. “All policy adjustments regarding PHEVs should be implemented with utmost caution and considering that evidence.”