🔗 Share this article

PHEVs produce almost five times greater planet-heating emissions than lab-reported figures show, according to a new report.

Widening Gap In Official and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, based on research carried out by a non-profit organization. That differs sharply with lab tests, which suggested a three-quarters reduction in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are falling,” stated a senior researcher participating in the study. “That gap is widening and creates a serious problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode compared to overall distance. The team determined that only a quarter of driving was done in EV mode, while official estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above official estimates. This occurred because EV motors were not strong enough to operate alone, resulting to combustion motors burning gasoline for almost a third of the distance covered in electric mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled four large automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend approximately €500 extra per year in running costs than is estimated under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly far from the truth,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from member states with significant automotive industries.

Some senior politicians have proposed plug-in hybrids as a potential “compromise” option to introduce in the regulation.

One external energy economics expert, who was unaffiliated with the research, described the report a “very useful addition” after a long period in which segments of the automotive sector claimed there was too little data to properly evaluate real-world emissions.

“The results show, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” they stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and considering that evidence.”