Plug-in Hybrid Vehicles Pollute Almost as Heavily as Gasoline Vehicles, Report Finds

Plug-in hybrid cars produce almost 5x greater planet-heating pollution than lab-reported data show, as per a recent report.

Widening Discrepancy In Official and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit group. That differs sharply with lab estimates, which suggested a 75% reduction in pollution.

Researchers studied data from onboard fuel consumption meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a senior analyst involved in the report. “That gap is widening and creates a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Researchers attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles travelled in battery power compared to total mileage. The team determined that just a quarter of driving was completed in electric mode, while lab estimates assumed over four-fifths.

Even, when running in electric mode, emission amounts were well above lab estimates. That occurred because electric motors were insufficiently powerful enough to operate alone, resulting to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 extra annually in running expenses than is assumed under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and resistance from EU countries with significant automotive industries.

Some high-level officials have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

An external energy policy specialist, who was not involved with the study, described the report a “highly valuable addition” after years in which segments of the automotive industry argued there was insufficient data to properly evaluate actual CO2 output.

“These findings demonstrate, without question, that the gap between official and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they said. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and considering this data.”