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PHEVs emit nearly five times more planet-heating pollution than official data show, according to a recent report.

Widening Discrepancy In Official and Real-World CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a non-profit group. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in emissions.

Analysts studied data from onboard energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” stated a lead analyst involved in the report. “This gap is growing and poses a serious problem. As a result, PHEVs pollute almost as much as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power compared to overall distance. They determined that only 27% of driving was completed in electric mode, while official estimates suggested over four-fifths.

Even, when running in electric mode, pollution levels were significantly higher than official estimates. That occurred because electric motors were not strong enough to function independently, resulting to engines burning fossil fuels for nearly a third of the travel covered in electric mode.

Policy and Economic Consequences

According to estimates, the underestimation of PHEV emissions allowed four large automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more per year in running costs than would be assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV cars are clearly far from the mark,” commented a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little improved than standard gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been brought again into policy discussions as carmakers have lobbied the EU to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant car manufacturing.

Some high-level politicians have suggested plug-in hybrids as a possible “compromise” option to include in the regulation.

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

“These findings demonstrate, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel cars,” they stated. “Any policy adjustments concerning PHEVs should be implemented with utmost caution and considering that data.”