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PHEVs release almost 5x more planet-heating pollution than official data indicate, according to a recent analysis.

Widening Discrepancy In Official and Real-World Emissions

Data reveals that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit group. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” stated a lead researcher participating in the report. “This discrepancy is growing and poses a serious issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in battery power compared to total distance. They determined that only a quarter of driving was done in electric mode, while lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than official estimates. That occurred because electric motors were not strong enough to function independently, resulting to engines using fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV emissions enabled four major automaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more per year in operating costs than is assumed under lab tests.

“The bold claims that automakers like to make about their PHEV cars are clearly far from the truth,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Discussion and Automotive Pressure

Hybrid vehicles have lately been drawn again into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with large car industries.

Several senior officials have proposed PHEVs as a possible “flexibility” solution to introduce in the legislation.

One external energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after years in which segments of the car sector claimed there was insufficient information to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional cars,” the expert said. “Any policy adjustments regarding PHEVs should be made with extreme care and considering this data.”