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Plug-in hybrid electric vehicles release almost 5x more global warming emissions than lab-reported figures show, as per a new analysis.

Widening Gap Between Lab and Actual CO2 Output

Data reveals that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. This contrasts significantly with laboratory tests, which assumed a three-quarters reduction in emissions.

Researchers examined data from in-vehicle fuel consumption meters of eight hundred thousand cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” stated a senior researcher involved in the report. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery power compared to overall distance. They determined that only 27% of driving was done in electric mode, while lab estimates assumed over four-fifths.

Even, when running in electric mode, pollution levels were significantly higher than official projections. This happened because electric motors were insufficiently powerful enough to function alone, leading to combustion motors using gasoline for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output enabled several large carmaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 more per year in running costs than would be assumed under lab conditions.

“The bold statements that automakers like to make about their PHEV cars are clearly way off the mark,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into policy discussions as carmakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and resistance from member states with significant car industries.

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

One external energy economics expert, who was unaffiliated with the research, described the report a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was too little information to properly evaluate real-world emissions.

“These findings show, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” the expert said. “All policy changes concerning PHEVs should be made with extreme care and considering this evidence.”