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Plug-in hybrid electric vehicles release almost five times more planet-heating emissions than lab-reported data indicate, according to a recent analysis.

Growing Discrepancy In Official and Actual CO2 Output

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a advocacy group. That contrasts significantly with laboratory tests, which suggested a 75% decrease in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a lead analyst participating in the report. “This gap is widening and poses a significant problem. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in electric power compared to total distance. The team determined that only a quarter of travel was completed in electric mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, emission levels were well above official projections. That occurred because electric motors were not strong sufficient to function alone, leading to engines using fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output allowed several major automaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more annually in running costs than is assumed under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly far from the truth,” stated a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been brought again into political discussions as carmakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with large automotive industries.

Some high-level officials have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One independent energy economics expert, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the automotive sector claimed there was too little data to accurately evaluate actual emissions.

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with utmost care and considering this data.”