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PHEVs emit almost 5x more planet-heating pollution than official data show, as per a new analysis.

Growing Gap Between Lab and Real-World CO2 Output

Data reveals that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy organization. That contrasts significantly with laboratory tests, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” stated a senior researcher participating in the report. “That discrepancy is widening and creates a serious problem. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in battery mode compared to total distance. The team determined that only a quarter of driving was done in EV mode, whereas official assumptions suggested 84%.

Even, when running in EV mode, emission levels were well above lab projections. That happened because EV motors were not strong sufficient to function alone, resulting to engines using gasoline for almost a third of the distance completed in electric mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed several large carmaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 extra annually in running costs than would be assumed under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been brought back into policy debates as automakers have lobbied the EU to relax CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with significant car industries.

Several high-level officials have suggested PHEVs as a possible “compromise” solution to introduce in the legislation.

One external energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after a long period in which parts of the car sector claimed there was too little data to accurately assess actual emissions.

“The results demonstrate, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” they said. “All regulatory adjustments concerning PHEVs should be made with extreme caution and in the light of this data.”