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Plug-in hybrid cars emit nearly five times greater global warming emissions than official figures show, according to a new analysis.

Growing Discrepancy In Lab and Real-World CO2 Output

Statistics shows that PHEVs release just 19% less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Researchers examined data from in-vehicle energy use monitors of 800,000 vehicles 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 estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” stated a lead analyst participating in the report. “This discrepancy is widening and poses a serious issue. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power relative to total distance. They found that just 27% of driving was done in electric mode, whereas official estimates assumed 84%.

Additionally, when running in EV mode, pollution amounts were well above official projections. This happened because electric motors were not strong enough to function independently, resulting to combustion motors using fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled several large automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

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

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the truth,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have recently been brought back into political debates as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant automotive industries.

Several senior politicians have proposed PHEVs as a possible “flexibility” solution to include in the legislation.

One external energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after years in which segments of the car sector claimed there was insufficient information to accurately assess real-world emissions.

“The results show, without question, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and in the light of that data.”