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PHEVs produce almost 5x more global warming pollution than lab-reported data indicate, according to a recent analysis.

Widening Gap In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit only 19% less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit group. That contrasts sharply with lab estimates, which suggested a 75% reduction in pollution.

Analysts studied information from in-vehicle energy use meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” stated a lead analyst participating in the report. “That gap is widening and creates a significant issue. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric power compared to overall mileage. The team found that only 27% of travel was completed in electric mode, while lab estimates suggested 84%.

Additionally, when running in EV mode, pollution amounts were well above official projections. This happened because electric motors were not strong enough to function alone, resulting to engines using gasoline for nearly a third of the distance completed in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output allowed several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 extra annually in running costs than would be assumed under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are clearly far from the mark,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into political discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with large automotive industries.

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

An independent energy economics specialist, who was unaffiliated with the research, called the report a “highly valuable contribution” after a long period in which parts of the automotive industry argued there was too little data to accurately evaluate actual emissions.

“These findings show, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” the expert stated. “All regulatory changes regarding PHEVs should be made with utmost caution and considering this data.”