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PHEVs produce nearly five times greater planet-heating emissions than lab-reported figures show, as per a recent analysis.

Widening Gap In Official and Real-World CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel cars, based on research conducted by a advocacy organization. This contrasts significantly with laboratory estimates, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle fuel consumption meters of 800,000 cars sold in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a senior researcher involved in the report. “That gap is growing and poses a serious problem. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in battery mode compared to total distance. They found that just a quarter of travel was completed in EV mode, whereas lab estimates suggested 84%.

Even, when operating in EV mode, emission amounts were well above lab estimates. This occurred because EV motors were insufficiently powerful enough to operate independently, leading to engines using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled four major carmaker groups to escape over €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 extra annually in operating costs than would be assumed under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV cars are obviously way off the mark,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from member states with significant car manufacturing.

Some high-level politicians have proposed plug-in hybrids as a potential “compromise” option to introduce in the regulation.

An independent energy policy specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which parts of the car industry argued there was too little information to accurately assess actual CO2 output.

“The results show, without question, that the difference in lab and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or conventional cars,” the expert said. “All policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of this evidence.”