🔗 Share this article

PHEVs release almost 5x more planet-heating pollution than lab-reported figures indicate, according to a new report.

Growing Gap In Official and Actual CO2 Output

Data reveals that PHEVs release just one-fifth less CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit organization. That contrasts sharply with laboratory estimates, which assumed a three-quarters 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 higher than lab figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a lead researcher involved in the report. “This gap is widening and poses a significant issue. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total distance. The team found that only 27% of travel was done in EV mode, whereas official assumptions suggested 84%.

Even, when operating in electric mode, emission amounts were significantly higher than official estimates. This occurred because EV motors were insufficiently powerful sufficient to operate alone, resulting to engines burning fossil fuels for almost a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled several large carmaker groups to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 extra per year in operating costs than is assumed under laboratory tests.

“The strong statements that automakers often promote about their plug-in hybrid cars are obviously far from the mark,” commented a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought back into political discussions as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with significant automotive industries.

Several senior politicians have suggested plug-in hybrids as a potential “flexibility” solution to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the study, described the report a “highly valuable addition” after years in which segments of the car sector argued there was too little information to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with utmost caution and considering this data.”