Plug in Hybrid electric Vehicles Emit Nearly as Heavily as Gasoline Cars, Study Reveals

Plug-in hybrid cars produce nearly five times more global warming pollution than official figures indicate, according to a recent report.

Widening Gap In Official and Actual Emissions

Data reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel cars, according to research conducted by a non-profit organization. That differs significantly with laboratory tests, which assumed a 75% decrease in pollution.

Researchers examined data from onboard energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” said a lead researcher participating in the study. “That discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Key Factors Driving the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric mode compared to total mileage. They determined that only a quarter of travel was completed in EV mode, while lab estimates suggested 84%.

Additionally, when running in EV mode, emission levels were significantly higher than lab projections. This occurred because electric motors were not strong enough to operate alone, leading to combustion motors burning gasoline for almost a third of the travel covered in EV mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions allowed four large carmaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 extra per year in operating costs than is estimated under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” commented a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid vehicles have lately been drawn again into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large automotive manufacturing.

Some senior politicians have suggested plug-in hybrids as a potential “compromise” option to include in the legislation.

One external energy economics expert, who was not involved with the research, described the analysis a “highly valuable addition” after years in which parts of the automotive industry claimed there was too little data to properly assess actual CO2 output.

“The results show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel vehicles,” they stated. “All regulatory changes regarding PHEVs should be made with extreme care and in the light of this data.”