2025 Civic Si Mpg. I only have five tanks through my new si so far, but i'm averaging 37.53 mpg, even driving the car kind of hard once in a while. Fuel economy keeps on pace with an easy task of hitting the epa figures in the real world of 27 mpg city, 37 mpg highway, and 31 mpg combined.
Your mileage will vary depending on how you drive and maintain your vehicle, driving conditions. Detailed specs and features for the 2025 honda civic si including dimensions, horsepower, engine, capacity, fuel economy, transmission, engine type, cylinders, drivetrain and more.