Fuel Choice and Deregulation Act of 2025

This bill modifies Clean Air Act regulations to expand vehicle fuel options. It allows aftermarket conversions of older vehicles to run on alternative fuels (like natural gas or biodiesel) without being classified as "tampering," provided they meet engineering standards and include required labels. It also creates a new "fuel choice enabling manufacturer" category for companies with 50%+ of their fleet as vehicles designed for non-petroleum fuels (e.g., plug-in electric, flexible fuel, or hydrogen), granting them an 8 MPG bonus in fuel economy calculations. Additionally, the bill prohibits EPA from regulating biomass fuels under the Clean Air Act and adjusts ethanol blending requirements. These changes apply to vehicles manufactured for model year 2026 and later.