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PHEVs emit nearly 5x more global warming pollution than lab-reported figures indicate, as per a new analysis.

Widening Gap In Lab and Actual CO2 Output

Data reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a advocacy organization. This differs significantly with laboratory estimates, which suggested a three-quarters decrease in emissions.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand cars sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while official figures are decreasing,” said a senior researcher involved in the report. “This discrepancy is widening and poses a serious problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode compared to total distance. The team found that just 27% of driving was done in EV mode, while official estimates assumed over four-fifths.

Additionally, when operating in electric mode, emission levels were well above official estimates. That happened because EV motors were not strong enough to operate alone, leading to engines burning gasoline for nearly a third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled several large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more annually in running costs than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are obviously way off the truth,” stated a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with large automotive industries.

Several senior officials have proposed PHEVs as a possible “flexibility” solution to include in the regulation.

One independent energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which parts of the automotive sector claimed there was insufficient information to accurately evaluate real-world emissions.

“These findings demonstrate, without question, that the gap between official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” they stated. “All regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of that data.”