Plug in Hybrid Cars Emit Nearly as Heavily as Gasoline Cars, Report Finds

Plug-in hybrid cars release almost 5x more planet-heating emissions than lab-reported data show, as per a new analysis.

Growing Gap Between Official and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, according to analysis carried out by a advocacy organization. This contrasts sharply with laboratory tests, which suggested a 75% reduction in pollution.

Researchers studied information from onboard energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” said a senior researcher participating in the report. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Key Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode compared to overall mileage. They found that just 27% of driving was done in electric mode, whereas lab estimates suggested over four-fifths.

Even, when operating in electric mode, emission levels were significantly higher than official projections. That occurred because EV motors were insufficiently powerful enough to operate independently, leading to combustion motors burning fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay approximately €500 extra annually in running costs than would be assumed under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than regular gas and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have recently been brought back into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a potential “compromise” solution to include in the legislation.

One external energy policy specialist, who was unaffiliated with the research, described the analysis a “very useful contribution” after years in which segments of the car sector argued there was too little information to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they stated. “All policy changes regarding PHEVs should be implemented with utmost care and considering this data.”