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Plug-in hybrid cars emit almost 5x more global warming pollution than lab-reported figures indicate, according to a recent analysis.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics shows that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to research carried out by a advocacy organization. This contrasts sharply with lab estimates, which suggested a 75% decrease in pollution.

Analysts studied information from onboard energy use meters of eight hundred thousand cars sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” stated a senior analyst participating in the report. “This gap is growing and poses a serious issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric power relative to overall distance. They determined that just a quarter of driving was done in electric mode, while official assumptions assumed over four-fifths.

Additionally, when operating in EV mode, pollution levels were well above lab estimates. This happened because electric motors were not strong sufficient to operate independently, leading to engines using fossil fuels for almost a third of the distance completed in electric mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV emissions allowed four major carmaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more per year in running costs than would be assumed under laboratory tests.

“The strong claims that manufacturers often promote about their PHEV cars are clearly way off the truth,” stated a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought back into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with significant car industries.

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

An external energy policy specialist, who was not involved with the study, called the analysis a “very useful contribution” after years in which segments of the car sector claimed there was insufficient data to properly evaluate real-world CO2 output.

“These findings show, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert said. “Any policy changes concerning PHEVs should be made with extreme caution and considering this data.”