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Plug-in hybrid cars produce almost 5x more planet-heating emissions than official data indicate, as per a new report.

Growing Gap In Lab and Real-World Emissions

Statistics shows that PHEVs release only 19% less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit group. This contrasts sharply with laboratory estimates, which assumed a 75% reduction in emissions.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” said a lead researcher involved in the report. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles driven in electric power relative to total distance. They determined that just 27% of travel was done in electric mode, whereas official estimates suggested over four-fifths.

Even, when running in electric mode, pollution amounts were well above lab estimates. That happened because EV motors were not strong enough to operate alone, leading to combustion motors using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output allowed four large carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 more annually in operating costs than is estimated under laboratory tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly far from the truth,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn again into policy debates as automakers have pressed the EU to weaken CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with significant automotive industries.

Several senior officials have suggested plug-in hybrids as a potential “compromise” solution to include in the regulation.

One independent energy economics expert, who was unaffiliated with the study, described the analysis a “very useful addition” after a long period in which parts of the car sector claimed there was too little information to accurately assess actual emissions.

“These findings show, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel cars,” they stated. “All regulatory changes regarding PHEVs should be made with utmost caution and considering that evidence.”