🔗 Share this article

Plug-in hybrid electric vehicles emit almost 5x more planet-heating emissions than lab-reported data show, as per a recent report.

Widening Discrepancy Between Lab and Actual CO2 Output

Statistics shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. That differs sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Researchers examined information from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a senior researcher participating in the study. “This gap is growing and creates a significant issue. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power compared to overall mileage. The team found that only 27% of driving was completed in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official estimates. This happened because electric motors were not strong enough to operate independently, resulting to combustion motors using gasoline for almost a third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV emissions enabled four major carmaker companies to avoid over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay about €500 more annually in operating costs than is assumed under laboratory tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Pressure

Hybrid cars have recently been drawn back into political discussions as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on new combustion engine cars in 2035 has faced heavy pressure from the car sector and resistance from EU countries with significant automotive manufacturing.

Some high-level politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

An independent energy economics expert, who was not involved with the study, described the analysis a “highly valuable addition” after years in which parts of the car industry argued there was insufficient information to properly assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert stated. “All policy changes regarding PHEVs should be made with extreme care and in the light of this data.”