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PHEVs release nearly 5x greater planet-heating emissions than official figures indicate, according to a new report.

Widening Gap In Official and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy group. This differs sharply with laboratory estimates, which assumed a 75% decrease in emissions.

Analysts studied information from in-vehicle energy use monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a senior researcher participating in the report. “This gap is widening and creates a serious issue. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode relative to overall distance. They found that just 27% of driving was completed in electric mode, while lab estimates suggested over four-fifths.

Even, when running in EV mode, pollution levels were well above official projections. This occurred because EV motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning gasoline for nearly a third of the travel completed in EV mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV CO2 output enabled four large automaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more per year in running costs than is estimated under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” commented a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been brought back into political discussions as automakers have lobbied the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large automotive industries.

Some senior officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the regulation.

An external energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after years in which parts of the car sector argued there was insufficient information to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap between official and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” they said. “All regulatory changes concerning PHEVs should be implemented with extreme caution and considering this evidence.”