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PHEVs emit almost 5x greater planet-heating pollution than official data indicate, according to a recent report.

Widening Gap In Official and Real-World Emissions

Data shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, according to analysis carried out by a non-profit organization. That differs sharply with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts studied data from in-vehicle energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that actual 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 official emissions are falling,” stated a senior researcher participating in the study. “That gap is growing and poses a significant issue. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power compared to total distance. The team determined that only a quarter of driving was completed in EV mode, while lab estimates suggested over four-fifths.

Even, when operating in EV mode, pollution levels were significantly higher than official estimates. This happened because EV motors were not strong sufficient to operate alone, resulting to engines using fossil fuels for almost one-third of the distance covered in electric mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to escape over €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend about €500 more annually in operating expenses than is estimated under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into political debates as automakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant automotive manufacturing.

Several senior officials have suggested plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

One external energy policy expert, who was not involved with the research, called the analysis a “highly valuable addition” after a long period in which parts of the car sector argued there was insufficient data to accurately assess actual emissions.

“These findings show, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” the expert stated. “All policy adjustments regarding PHEVs should be made with utmost caution and in the light of this data.”