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Plug-in hybrid electric vehicles produce nearly 5x greater global warming pollution than official figures indicate, according to a recent report.

Widening Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, according to analysis conducted by a non-profit group. This contrasts sharply with lab tests, which suggested a three-quarters reduction in pollution.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 vehicles registered in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” said a lead analyst involved in the report. “This discrepancy is widening and creates a significant problem. Consequently, PHEVs emit nearly as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode compared to overall distance. The team found that just a quarter of travel was done in EV mode, while official assumptions suggested over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than official projections. This occurred because EV motors were not strong enough to operate alone, leading to combustion motors burning fossil fuels for nearly a third of the distance completed in electric mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output allowed four major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend approximately €500 more annually in running expenses than is estimated under laboratory conditions.

“The strong statements that automakers often promote about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been brought back into political debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced intense pressure from the car sector and opposition from member states with significant car manufacturing.

Several high-level officials have proposed PHEVs as a possible “compromise” option to introduce in the legislation.

One external energy economics expert, who was not involved with the research, described the analysis a “highly valuable addition” after years in which segments of the automotive industry claimed there was insufficient information to properly assess actual CO2 output.

“These findings show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional vehicles,” the expert stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme care and considering that evidence.”