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PHEVs release almost 5x greater global warming pollution than lab-reported data indicate, as per a new report.

Growing Gap In Official and Actual Emissions

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, according to research conducted by a non-profit organization. That differs sharply with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts examined data from in-vehicle energy use monitors of 800,000 cars registered in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a senior analyst involved in the report. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Primary Reasons Behind the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in battery mode compared to overall mileage. They determined that only a quarter of travel was done in electric mode, while lab assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution levels were well above official estimates. This happened because electric motors were not strong enough to operate independently, leading to engines using fossil fuels for almost one-third of the distance covered in EV mode.

Policy and Economic Consequences

According to estimates, the underestimation of PHEV emissions allowed four large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 extra per year in operating costs than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their PHEV cars are obviously far from the mark,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have recently been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with large car industries.

Some senior officials have suggested PHEVs as a potential “compromise” option to introduce in the regulation.

An external energy policy specialist, who was not involved with the study, described the analysis a “highly valuable contribution” after years in which parts of the car industry argued there was too little data to accurately assess actual emissions.

“The results show, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert stated. “All policy changes regarding PHEVs should be made with extreme caution and in the light of that evidence.”