Plug in Hybrid Vehicles Emit Nearly as Much as Gasoline Cars, Study Reveals

Plug-in hybrid electric vehicles release almost five times greater planet-heating emissions than lab-reported data show, according to a new analysis.

Growing Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy organization. That differs sharply with lab tests, which assumed a three-quarters reduction in pollution.

Analysts studied data from in-vehicle fuel consumption meters of 800,000 vehicles registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” said a senior researcher participating in the study. “That gap is widening and creates a significant problem. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric power relative to overall distance. The team determined that only a quarter of travel was done in electric mode, while lab assumptions assumed 84%.

Even, when operating in electric mode, pollution levels were significantly higher than lab estimates. This happened because EV motors were not strong sufficient to operate alone, leading to engines using gasoline for almost a third of the distance covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled several large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more annually in operating costs than would be estimated under laboratory tests.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” stated a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Pressure

Hybrid vehicles have lately been brought back into policy discussions as automakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced heavy pressure from the car industry and resistance from member states with large car industries.

Several senior politicians have suggested PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy policy specialist, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which segments of the car sector argued there was too little data to accurately assess real-world CO2 output.

“These findings demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they stated. “Any regulatory changes regarding PHEVs should be made with utmost care and in the light of that evidence.”