Plug-in Hybrid Vehicles Pollute Almost as Heavily as Petrol Cars, Study Reveals

Plug-in hybrid electric vehicles emit nearly 5x greater global warming pollution than lab-reported data indicate, according to a new analysis.

Growing Gap In Official and Actual CO2 Output

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a advocacy organization. This differs sharply with laboratory tests, which suggested a three-quarters decrease in pollution.

Analysts examined data from onboard 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 nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a lead analyst participating in the study. “This discrepancy is widening and creates a serious issue. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery power compared to overall mileage. They determined that only a quarter of travel was completed in EV mode, whereas lab assumptions suggested 84%.

Additionally, when running in electric mode, emission levels were significantly higher than official projections. That happened because electric motors were insufficiently powerful sufficient to function independently, leading to combustion motors using fossil fuels for almost one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed several large carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 more per year in operating expenses than is estimated under laboratory tests.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” stated a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into political debates as carmakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with large automotive manufacturing.

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

One independent energy policy specialist, who was unaffiliated with the research, called the report a “very useful contribution” after a long period in which segments of the automotive industry claimed there was insufficient information to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or diesel vehicles,” they stated. “All regulatory changes regarding PHEVs should be implemented with extreme caution and considering that evidence.”