Plug-in Hybrid electric Cars Emit Almost as Heavily as Gasoline Vehicles, Report Finds

Plug-in hybrid electric vehicles emit almost five times greater planet-heating emissions than official figures show, according to a recent analysis.

Growing Discrepancy Between Official and Real-World Emissions

Data shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit organization. That differs significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts examined information from onboard fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ output 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 figures are decreasing,” said a senior analyst involved in the report. “This discrepancy is growing and creates a significant problem. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Factors Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in battery power compared to total mileage. The team determined that only a quarter of travel was done in EV mode, whereas lab estimates suggested over four-fifths.

Even, when running in EV mode, pollution levels were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful enough to operate independently, leading to combustion motors using gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed four major carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend about €500 extra annually in operating expenses than would be assumed under lab tests.

“The strong claims that manufacturers like to make about their PHEV cars are clearly way off the mark,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Pressure

Hybrid vehicles have recently been brought back into political debates as carmakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and opposition from member states with significant automotive industries.

Some high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after years in which parts of the car sector argued there was insufficient data to accurately evaluate actual emissions.

“These findings demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional vehicles,” they said. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and in the light of this evidence.”