Share your car details, what is the mileage, what oil you are using. This model with auto transmission gives 10-10.5 kmpl in city with AC. 16.5 on highway. Personally verified with 3 cars, all autos. Also, you will hear people whine about "rebon ki fool average" while they have no idea how to maintain the car. Poor fuel mileage in civic 8th gen is usually due to few reasons:
Non genuine air filter (YES- makes a difference)
Oil Grade should be 5w30. any more viscous oil and this engine isnt going to perform upto spec.
Thermostat valve must be operational and honda type 2 coolant must be used. If engine isnt working on optimum temperature, it will run rich and will give bad mileage.
Fuel pump and filter replacement per spec.
Spark Plug replacemsnt on 60k km
If its auto: Condition of transmission, if its slipping, its gonna give worse mileage.
Brakes should be inspected, seized caliper pins will cause wheels to drag, hence poor fuel economy.
These are the basics, check them out one by one. Then proceed to check the DTCs of engine and resolve if any.
Edit: Check your wheel and tyre size aswell. Its 195/65/15 as per spec. wider tires or bigger wheels will hurt economy aswell by a big margin.
