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

PHEVs produce nearly five times greater global warming emissions than official data show, according to a new report.

Widening Gap Between Official and Real-World CO2 Output

Data shows that PHEVs release only 19% less CO₂ than traditional petrol and diesel cars, based on analysis conducted by a advocacy group. That differs sharply with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts studied information from onboard fuel consumption meters of 800,000 cars sold in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” said a lead analyst participating in the report. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in electric mode compared to total distance. The team determined that just a quarter of travel was completed in EV mode, while official estimates suggested 84%.

Even, when running in EV mode, emission levels were significantly higher than official projections. This happened because EV motors were not strong enough to function independently, resulting to engines using gasoline for almost one-third of the travel covered in electric mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV emissions allowed four major automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 more per year in operating expenses than is assumed under laboratory tests.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are obviously far from the truth,” stated a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with significant car industries.

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

One independent energy policy expert, who was unaffiliated with the study, described the report a “highly valuable addition” after years in which segments of the automotive industry claimed there was insufficient information to accurately evaluate actual CO2 output.

“The results show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they stated. “All policy adjustments concerning PHEVs should be made with utmost caution and considering that evidence.”