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Plug-in hybrid cars emit almost five times more planet-heating pollution than lab-reported figures indicate, as per a recent report.

Widening Gap Between Official and Actual CO2 Output

Data shows that PHEVs release only 19% less CO₂ than traditional gas and diesel vehicles, according to research carried out by a non-profit group. This differs sharply with lab tests, which suggested a 75% reduction in emissions.

Analysts examined information from onboard energy use meters of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher involved in the report. “That discrepancy is widening and poses a serious issue. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode compared to total distance. The team determined that just a quarter of travel was completed in EV mode, whereas lab estimates suggested 84%.

Additionally, when running in electric mode, pollution amounts were well above official projections. This occurred because electric motors were not strong enough to function independently, resulting to engines burning gasoline for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled several large automaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more annually in operating costs than is estimated under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” stated a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have recently been drawn again into political debates as automakers have pressed the EU to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car manufacturing.

Several senior officials have suggested PHEVs as a possible “compromise” solution to include in the legislation.

One external energy economics expert, who was unaffiliated with the study, described the report a “highly valuable addition” after a long period in which segments of the car industry claimed there was too little data to accurately evaluate actual CO2 output.

“The results show, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” the expert said. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and considering this evidence.”