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PHEVs produce almost 5x more planet-heating emissions than lab-reported figures indicate, as per a new report.

Growing Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, according to research carried out by a non-profit group. This contrasts sharply with lab estimates, which assumed a 75% decrease in emissions.

Researchers studied data from onboard fuel consumption monitors of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a lead analyst participating in the study. “That discrepancy is widening and poses a significant issue. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric power relative to overall mileage. The team determined that just a quarter of driving was done in EV mode, whereas official assumptions assumed over four-fifths.

Additionally, when operating in electric mode, pollution levels were significantly higher than official projections. That happened because EV motors were not strong sufficient to operate independently, leading to combustion motors using gasoline for almost a third of the travel covered in EV mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV emissions allowed several major automaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 extra annually in running expenses than would be estimated under lab conditions.

“The bold claims that automakers often promote about their PHEV vehicles are obviously way off the mark,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little better than standard gas and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into political debates as automakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and resistance from member states with large car industries.

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

One independent energy policy specialist, who was not involved with the research, described the analysis a “highly valuable addition” after years in which segments of the car sector argued there was too little information to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” they stated. “Any regulatory adjustments concerning PHEVs should be made with extreme caution and in the light of that evidence.”