🔗 Share this article

Plug-in hybrid cars emit nearly 5x greater global warming emissions than lab-reported figures show, according to a new analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics shows that PHEVs release only 19% lower CO₂ than traditional gas and diesel cars, based on analysis carried out by a advocacy organization. That differs significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts studied information from in-vehicle energy use monitors of 800,000 cars sold in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a senior analyst participating in the study. “This discrepancy is growing and creates a significant issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Factors Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode compared to overall mileage. They determined that just a quarter of driving was done in EV mode, whereas official estimates suggested over four-fifths.

Even, when running in EV mode, emission amounts were well above official projections. That occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors burning fossil fuels for nearly one-third of the distance completed in EV mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled several large carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra per year in running expenses than would be estimated under lab tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” commented a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have recently been drawn back into political discussions as carmakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant automotive manufacturing.

Some senior politicians have suggested PHEVs as a potential “compromise” solution to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the car sector argued there was too little data to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert stated. “Any policy changes regarding PHEVs should be implemented with utmost caution and in the light of that evidence.”