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Plug-in hybrid electric vehicles produce almost five times greater global warming pollution than official data show, as per a recent analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Data reveals that PHEVs emit just 19% less CO₂ than traditional petrol and diesel cars, based on analysis conducted by a non-profit group. This differs sharply with lab estimates, which assumed a 75% decrease in emissions.

Analysts studied information from in-vehicle energy use meters of 800,000 vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” stated a lead analyst involved in the study. “This discrepancy is widening and poses a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in battery power relative to total distance. They determined that only a quarter of travel was done in EV mode, whereas official assumptions assumed 84%.

Additionally, when running in EV mode, emission levels were significantly higher than lab projections. That happened because EV motors were not strong enough to function alone, resulting to combustion motors burning gasoline for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV emissions allowed several large carmaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more annually in running expenses than would be assumed under lab tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have recently been drawn back into policy discussions as automakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the car sector and opposition from member states with significant automotive industries.

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

One external energy economics expert, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which segments of the automotive industry claimed there was insufficient data to accurately evaluate actual emissions.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is significantly larger than for petrol or diesel vehicles,” they stated. “Any policy changes regarding PHEVs should be implemented with extreme caution and in the light of that evidence.”