2025 Civic Si Mpg Specs. 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. 31 mpg (u.s.), 7.6 l/100km, 37.2 mpg (imp.), 13.2 km/l new epa combined ratings;

Horsepower (sae net)* 200 hp @ 6,000 rpm. Find information on performance, specs, engine, safety and more.