🔗 Share this article

Plug-in hybrid cars produce almost 5x more planet-heating emissions than lab-reported data show, according to a new report.

Growing Gap In Official and Real-World CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy organization. This differs significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” said a senior researcher involved in the study. “This gap is growing and creates a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode compared to overall mileage. They found that only a quarter of driving was done in electric mode, while official estimates assumed over four-fifths.

Even, when running in electric mode, pollution amounts were well above official estimates. That happened because electric motors were insufficiently powerful sufficient to operate alone, leading to combustion motors burning fossil fuels for almost one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed four major carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 extra annually in running costs than is assumed under lab conditions.

“The bold statements that automakers like to make about their PHEV vehicles are clearly far from the truth,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been brought again into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with significant automotive industries.

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

An independent energy policy expert, who was not involved with the study, called the report a “highly valuable addition” after a long period in which parts of the automotive industry claimed there was too little information to properly evaluate real-world emissions.

“These findings show, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” the expert said. “Any policy changes concerning PHEVs should be made with utmost care and considering this data.”