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PHEVs produce nearly five times more planet-heating emissions than lab-reported figures show, according to a recent analysis.

Growing Gap In Official and Real-World Emissions

Statistics reveals that PHEVs release only one-fifth lower CO₂ than conventional gas and diesel cars, according to analysis conducted by a advocacy organization. That differs significantly with laboratory tests, which suggested a 75% reduction in emissions.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” stated a lead researcher involved in the report. “That discrepancy is widening and poses a significant problem. As a result, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles travelled in battery power compared to overall mileage. They found that only a quarter of driving was done in EV mode, while lab estimates assumed 84%.

Additionally, when running in electric mode, pollution levels were well above official estimates. This happened because EV motors were insufficiently powerful enough to operate alone, leading to combustion motors using fossil fuels for nearly a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled several major automaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 extra annually in running costs than would be estimated under laboratory tests.

“The bold claims that automakers like to make about their PHEV vehicles are clearly far from the mark,” commented a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little better than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have lately been drawn back into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with large car industries.

Some senior officials have proposed PHEVs as a potential “compromise” solution to include in the legislation.

An independent energy economics expert, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which parts of the automotive industry argued there was insufficient data to accurately evaluate real-world CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” the expert stated. “Any policy adjustments concerning PHEVs should be implemented with extreme caution and considering this data.”