As of January 1, 2025, the automotive industry entered a high-stakes era of “CO2 compliance.” While the headlines have focused on the survival of the internal combustion engine, the immediate reality for consumers is a significant shift in the cost of hybrid technology.

The primary driver of this shift is the Euro 6e-bis standard and the updated WLTP (Worldwide Harmonized Light Vehicles Test Procedure), which have fundamentally changed how hybrid efficiency is calculated.

1. The “Utility Factor” Price Hike for PHEVs

The most direct impact has been on Plug-in Hybrids (PHEVs). In 2025, the EU implemented a revised “Utility Factor,” which assumes that drivers use the electric-only mode less frequently than previously estimated.

• The Result: Many PHEVs that were officially rated at $50\text{g/km}$ of CO2 in 2024 have seen their official ratings jump to $90\text{g/km}$ or higher.
• Price Impact: Because higher emissions lead to higher taxes and potential