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Plug-in hybrid cars produce almost 5x more planet-heating emissions than lab-reported figures show, as per a new report.

Widening Gap Between Official and Real-World Emissions

Data shows that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a advocacy organization. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts studied information from in-vehicle energy use meters of eight hundred thousand cars sold in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are falling,” said a senior analyst involved in the study. “This gap is growing and poses a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Behind the Emissions Gap

Researchers linked most of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to overall mileage. They determined that only 27% of driving was completed in EV mode, while lab estimates 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 function independently, leading to combustion motors using fossil fuels for almost a third of the distance completed in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV emissions enabled several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would pay approximately €500 extra per year in operating expenses than is assumed under laboratory conditions.

“The bold statements that automakers like to make about their PHEV cars are clearly way off the truth,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid vehicles have lately been drawn back into political debates as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car industry and resistance from EU countries with significant automotive industries.

Several senior politicians have proposed PHEVs as a potential “compromise” solution to introduce in the legislation.

An external energy policy expert, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which parts of the car sector argued there was too little data to properly assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they said. “All policy changes regarding PHEVs should be implemented with extreme care and in the light of this evidence.”