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PHEVs emit almost five times greater global warming emissions than official figures indicate, according to a recent analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs release only 19% lower CO₂ than traditional petrol and diesel vehicles, according to research carried out by a advocacy group. That differs significantly with laboratory estimates, which assumed a 75% decrease in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a lead researcher involved in the study. “That discrepancy is widening and poses a significant issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Driving the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in electric mode compared to overall distance. The team determined that only 27% of travel was done in electric mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, emission levels were significantly higher than lab estimates. That happened because electric motors were not strong enough to function independently, resulting to combustion motors burning fossil fuels for nearly one-third of the distance covered in electric mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV emissions enabled four major automaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 more per year in running costs than is assumed under lab conditions.

“The strong statements that manufacturers often promote about their PHEV vehicles are clearly way off the truth,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving money. Actually, PHEVs are little better than regular gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with large automotive industries.

Some high-level politicians have proposed PHEVs as a potential “compromise” solution to include in the legislation.

One external energy policy expert, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which segments of the automotive sector argued there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel vehicles,” the expert stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering that evidence.”