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PHEVs release nearly 5x greater planet-heating pollution than official data show, according to a new analysis.

Widening Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs release only 19% lower CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy organization. This contrasts significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied information from onboard fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a lead researcher involved in the report. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in electric mode relative to total distance. They determined that just 27% of travel was done in electric mode, while official assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution levels were well above lab estimates. That occurred because EV motors were not strong sufficient to operate alone, resulting to combustion motors using fossil fuels for almost one-third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled four large automaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more per year in operating costs than is estimated under laboratory tests.

“The strong claims that automakers like to make about their PHEV vehicles are obviously way off the mark,” stated a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn back into political debates as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with large automotive manufacturing.

Several senior officials have proposed plug-in hybrids as a potential “flexibility” option to introduce in the regulation.

An external energy policy specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after years in which parts of the automotive industry argued there was insufficient data to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional cars,” the expert stated. “All regulatory changes concerning PHEVs should be implemented with utmost care and in the light of this evidence.”