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Plug-in hybrid cars emit almost 5x more planet-heating emissions than lab-reported figures indicate, according to a new analysis.

Growing Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a advocacy group. This contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined data from onboard energy use meters of 800,000 cars registered 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 estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a lead analyst participating in the report. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to overall distance. The team found that only 27% of travel was done in electric mode, whereas lab estimates assumed 84%.

Even, when operating in EV mode, emission levels were significantly higher than lab projections. This happened because electric motors were insufficiently powerful enough to function independently, resulting to engines burning fossil fuels for nearly a third of the distance covered in EV mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV emissions enabled four major automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more annually in running costs than is assumed under laboratory tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously far from the truth,” commented a automotive expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Hybrid vehicles have lately been brought again into policy discussions as carmakers have pressed the European Union to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from member states with significant automotive industries.

Some senior politicians have proposed plug-in hybrids as a potential “flexibility” option to include in the regulation.

One independent energy policy specialist, who was not involved with the research, described the report a “highly valuable contribution” after a long period in which parts of the car sector claimed there was too little information to accurately assess real-world emissions.

“These findings demonstrate, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel cars,” the expert said. “Any policy changes concerning PHEVs should be implemented with utmost care and considering this data.”