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Plug-in hybrid cars produce almost five times greater planet-heating emissions than lab-reported figures show, according to a new analysis.

Widening Gap In Official and Actual CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel cars, based on research conducted by a non-profit group. This contrasts significantly with lab tests, which assumed a three-quarters decrease in pollution.

Analysts examined data from onboard energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” said a senior researcher participating in the report. “That gap is growing and poses a significant issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery power compared to overall distance. The team determined that just a quarter of travel was done in EV mode, whereas official assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution amounts were well above official estimates. This happened because electric motors were not strong sufficient to operate independently, resulting to engines using fossil fuels for almost a third of the travel covered in EV mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions allowed several major automaker companies to escape more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 more annually in operating expenses than is assumed under laboratory tests.

“The bold statements that automakers like to make about their PHEV cars are obviously far from the mark,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have lately been brought back into political discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant car manufacturing.

Some senior officials have suggested plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

One independent energy economics expert, who was not involved with the research, described the analysis a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient data to properly evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel cars,” the expert stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and considering this evidence.”