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PHEVs release nearly five times more global warming emissions than lab-reported figures show, according to a new analysis.

Growing Discrepancy In Lab and Actual CO2 Output

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, based on research conducted by a advocacy group. That differs significantly with laboratory estimates, which suggested a three-quarters decrease in emissions.

Analysts studied information from onboard energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” stated a lead researcher involved in the report. “That gap is widening and creates a significant issue. As a result, PHEVs emit almost as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric mode compared to overall mileage. The team found that just 27% of driving was completed in EV mode, while lab assumptions assumed over four-fifths.

Even, when running in electric mode, emission amounts were significantly higher than official projections. This happened because EV motors were not strong enough to operate alone, resulting to engines using fossil fuels for almost a third of the distance covered in electric mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more annually in running expenses than would be estimated under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly far from the mark,” commented a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving money. Actually, PHEVs are little better than standard gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought back into policy debates as automakers have pressed the EU to weaken CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large car manufacturing.

Some high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the legislation.

An independent energy policy specialist, who was not involved with the research, called the report a “very useful contribution” after a long period in which parts of the automotive industry argued there was insufficient information to properly evaluate actual emissions.

“These findings show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and considering that evidence.”