Plug-in Hybrid electric Cars Pollute Almost as Heavily as Gasoline Cars, Study Reveals

PHEVs emit nearly 5x more global warming emissions than lab-reported data indicate, according to a new report.

Widening Gap Between Lab and Real-World Emissions

Data shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy organization. That differs significantly with lab tests, which suggested a 75% decrease in emissions.

Analysts studied data from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are decreasing,” said a senior analyst involved in the study. “That discrepancy is widening and poses a significant issue. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric mode compared to overall distance. The team found that just 27% of travel was completed in electric mode, while lab estimates suggested 84%.

Additionally, when operating in EV mode, emission levels were well above lab estimates. This occurred because electric motors were not strong sufficient to function alone, resulting to combustion motors using gasoline for almost one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV emissions allowed four large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 extra annually in operating costs than is assumed under laboratory conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Industry Lobbying

Hybrid cars have recently been brought back into political discussions as carmakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and opposition from member states with significant car industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An external energy economics expert, who was unaffiliated with the research, described the report a “very useful addition” after a long period in which parts of the car industry argued there was too little information to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” the expert said. “Any policy changes concerning PHEVs should be made with extreme caution and considering this data.”