Plug-in Hybrid Vehicles Emit Nearly as Much as Petrol Vehicles, Study Reveals

PHEVs produce nearly 5x greater global warming emissions than lab-reported data indicate, as per a recent report.

Growing Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel vehicles, according to research carried out by a non-profit group. That differs sharply with laboratory tests, which suggested a 75% decrease in emissions.

Analysts studied data from in-vehicle energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” stated a senior analyst participating in the study. “This gap is widening and creates a significant issue. As a result, PHEVs emit almost as heavily as petrol cars.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery mode relative to total mileage. They found that just a quarter of driving was done in EV mode, while lab estimates assumed 84%.

Additionally, when running in electric mode, pollution levels were well above lab estimates. This occurred because EV motors were insufficiently powerful sufficient to function independently, leading to engines burning fossil fuels for nearly one-third of the distance covered in electric mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV emissions enabled several major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 extra per year in running costs than would be assumed under laboratory tests.

“The strong statements that automakers often promote about their PHEV vehicles are obviously far from the truth,” commented a transport expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little improved than regular gas and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have recently been drawn back into political debates as automakers have pressed the European Union to weaken CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant automotive industries.

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

One external energy policy expert, who was unaffiliated with the research, described the analysis a “highly valuable addition” after years in which segments of the car sector claimed there was too little data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” they said. “Any regulatory adjustments regarding PHEVs should be made with utmost caution and in the light of that evidence.”