Plug in Hybrid electric Vehicles Emit Almost as Heavily as Petrol Cars, Study Finds

Plug-in hybrid cars produce almost five times more global warming emissions than official figures show, as per a new analysis.

Growing Gap In Lab and Real-World Emissions

Data reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a advocacy organization. That differs significantly with laboratory estimates, which assumed a three-quarters reduction in pollution.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior researcher involved in the study. “This gap is growing and poses a significant problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric power compared to total distance. The team determined that only a quarter of travel was done in electric mode, whereas lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than official projections. This happened because electric motors were insufficiently powerful sufficient to operate alone, leading to combustion motors burning gasoline for nearly a third of the distance covered in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV emissions allowed several large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 extra per year in running expenses than would be estimated under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have recently been drawn again into political debates as automakers have pressed the EU to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with large car manufacturing.

Several high-level officials have suggested plug-in hybrids as a potential “compromise” option to include in the legislation.

One external energy policy expert, who was not involved with the research, called the analysis a “very useful contribution” after years in which parts of the automotive industry argued there was too little data to accurately evaluate actual CO2 output.

“The results show, without question, that the difference in lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” the expert said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and considering that evidence.”