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Plug-in hybrid cars produce almost 5x greater global warming emissions than official figures show, according to a recent report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy group. This differs sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” stated a senior researcher participating in the report. “That gap is widening and creates a significant issue. As a result, PHEVs emit almost as much as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts linked most of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric power relative to total distance. The team found that just 27% of travel was done in EV mode, whereas lab assumptions assumed 84%.

Even, when running in electric mode, pollution amounts were well above lab projections. This occurred because electric motors were not strong enough to operate independently, leading to engines burning fossil fuels for nearly a third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions allowed four large automaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend approximately €500 more per year in running costs than is assumed under laboratory conditions.

“The bold claims that automakers like to make about their PHEV vehicles are obviously way off the truth,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Industry Lobbying

Hybrid vehicles have lately been drawn again into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and resistance from EU countries with significant car manufacturing.

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

An external energy economics specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which segments of the car industry claimed there was insufficient information to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” they said. “All policy changes regarding PHEVs should be made with extreme care and in the light of that evidence.”