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PHEVs produce almost 5x more global warming emissions than lab-reported data show, according to a recent analysis.

Widening Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy organization. That differs sharply with lab estimates, which suggested a three-quarters decrease in emissions.

Analysts examined information from in-vehicle energy use meters of 800,000 cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” said a senior analyst participating in the report. “That gap is widening and creates a significant problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in electric power relative to total mileage. The team found that just 27% of travel was completed in EV mode, whereas lab estimates suggested 84%.

Additionally, when operating in EV mode, pollution levels were significantly higher than lab estimates. That occurred because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors using fossil fuels for nearly a third of the travel completed in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV emissions allowed four major carmaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra annually in operating expenses than is estimated under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Hybrid cars have recently been brought again into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car sector and resistance from member states with significant car industries.

Some senior politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

One independent energy policy expert, who was unaffiliated with the study, described the report a “very useful contribution” after a long period in which segments of the car sector claimed there was too little information to properly evaluate real-world emissions.

“The results show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional cars,” the expert stated. “All policy changes concerning PHEVs should be implemented with extreme caution and considering that data.”