Plug-in Hybrids Emit 6 Times, On Average, What Official Tests Claim — New EU Data

New data from the European Union shows plug-in hybrid cars (PHEVs, which pair a battery with a gas or diesel engine) pollute far more in real driving than official lab tests suggest. For cars registered in 2024, real-world emissions averaged 145 grams of CO2 per kilometer, compared to just 24 grams per kilometer in official tests — six times higher. That gap has grown every year since real-world tracking began in 2021, even as automakers claim PHEV performance is improving. At these real-world levels, PHEVs pollute only 14% less than plain gas-powered cars, not the deep cuts their official ratings imply.

The findings matter for anyone comparing PHEVs to fully electric cars or standard hybrids when shopping for a vehicle. The gap exists partly because PHEVs are tested under conditions that don't match how people actually drive them — many owners apparently rely on the gas engine more than the battery in daily use. The EU had planned rule changes in 2025 and 2027 to correct these official ratings and close the gap, but carmakers are now lobbying to cancel the 2027 update.

This is a European regulatory fight, not a US program, so it doesn't directly affect rebates or rules here. But it's useful context if you're weighing a plug-in hybrid: the sticker emissions and fuel-economy numbers may not reflect what you actually get once the car is in your driveway. The EU Council is expected to debate the issue on October 12, with a Parliament vote in November.