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

Widening Gap In Lab and Actual CO2 Output

Statistics reveals that PHEVs release only one-fifth less CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy organization. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a senior analyst involved in the study. “This discrepancy is widening and poses a serious problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery mode relative to overall mileage. They determined that just a quarter of travel was completed in EV mode, while lab assumptions suggested over four-fifths.

Even, when running in electric mode, emission levels were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful enough to function alone, resulting to engines using gasoline for almost one-third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output enabled several large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more annually in running expenses than would be assumed under laboratory conditions.

“The strong statements that automakers often promote about their PHEV vehicles are obviously far from the mark,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Hybrid cars have recently been drawn again into policy discussions as automakers have pressed the European Union to relax CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with significant car industries.

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

One independent energy policy expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry argued there was insufficient data to accurately assess real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel cars,” they said. “Any regulatory adjustments concerning PHEVs should be made with extreme care and considering this data.”