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PHEVs emit nearly five times greater planet-heating pollution than official data indicate, according to a recent analysis.

Widening Gap In Lab and Actual Emissions

Data reveals that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel cars, according to analysis carried out by a advocacy organization. That differs significantly with laboratory tests, which assumed a three-quarters decrease in emissions.

Researchers examined data from in-vehicle energy use monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” stated a lead researcher involved in the report. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in electric power compared to overall distance. The team found that just 27% of driving was completed in electric mode, while official estimates suggested over four-fifths.

Even, when running in EV mode, pollution levels were significantly higher than official projections. This occurred because EV motors were not strong enough to function independently, resulting to engines burning gasoline for nearly a third of the distance covered in EV mode.

Policy and Financial Consequences

According to estimates, the underestimation of PHEV emissions allowed four large automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 more annually in running expenses than would be estimated under laboratory tests.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little better than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Policy Debate and Automotive Pressure

Hybrid vehicles have recently been brought again into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car industries.

Some senior officials have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

One independent energy policy expert, who was not involved with the study, called the analysis a “very useful addition” after a long period in which parts of the car industry argued there was too little data to accurately evaluate real-world CO2 output.

“These findings demonstrate, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert stated. “Any policy adjustments regarding PHEVs should be made with extreme care and considering this data.”