Plug-in Hybrid electric Vehicles Pollute Almost as Heavily as Gasoline Vehicles, Report Reveals

Plug-in hybrid cars emit almost 5x more planet-heating emissions than lab-reported data indicate, according to a new report.

Widening Discrepancy In Official and Real-World Emissions

Data reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, based on research conducted by a non-profit group. That differs sharply with lab tests, which suggested a three-quarters decrease in pollution.

Researchers studied data from onboard fuel consumption meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” said a lead researcher participating in the study. “That discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in battery power compared to overall mileage. The team determined that just 27% of driving was completed in electric mode, whereas lab assumptions suggested 84%.

Even, when operating in EV mode, pollution amounts were significantly higher than lab projections. This happened because EV motors were not strong sufficient to function independently, leading to engines using fossil fuels for almost a third of the distance completed in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 extra annually in running costs than is estimated under laboratory conditions.

“The bold statements that automakers like to make about their PHEV vehicles are clearly far from the mark,” stated a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Discussion and Industry Lobbying

Hybrid cars have lately been drawn again into policy discussions as automakers have pressed the European Union to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and resistance from member states with large car manufacturing.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the research, called the report a “very useful contribution” after a long period in which segments of the automotive sector argued there was insufficient data to accurately evaluate actual CO2 output.

“These findings demonstrate, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” they said. “Any regulatory changes concerning PHEVs should be implemented with extreme care and in the light of this evidence.”