Plug in Hybrid Cars Pollute Nearly as Much as Gasoline Cars, Report Reveals

PHEVs emit almost 5x greater planet-heating pollution than lab-reported data show, according to a new report.

Widening Discrepancy In Lab and Real-World CO2 Output

Data shows that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. This contrasts significantly with lab tests, which suggested a 75% reduction in pollution.

Researchers examined data from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to overall mileage. The team determined that only 27% of travel was completed in EV mode, while official estimates suggested 84%.

Additionally, when running in electric mode, pollution amounts were significantly higher than official estimates. That occurred because EV motors were insufficiently powerful enough to function independently, resulting to engines burning gasoline for almost a third of the distance covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions allowed several large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 extra per year in operating costs than is estimated under laboratory tests.

“The bold statements that automakers often promote about their PHEV cars are clearly way off the truth,” stated a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been brought back into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the car sector and resistance from member states with significant car manufacturing.

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

One external energy economics specialist, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry argued there was insufficient information to properly evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they said. “All regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this data.”