Man you are more idiot than I thought. Trip meter/speedometer is 99% accurate. It has been accurate for 100 years. In most older cars (and still in most brand new Suzuki cars), there is a mechanical cable going from gearbox to odometer where small tooth wheels spin with that cable and move the digits and speed needle. While in new and expensive cars, there is a sensor connected with a moving gear in gearbox and measure its speed and send signal to ECU which in turn display figures on the odometer and also move the speed needle with a motor.
While the "average per kilometer" shown on your meter has different story. ECU considers air-to-fuel ratio, speed of car, gear in which you are driving, RPM and then gives you an estimate. Now if you are an imbecile, you would believe that to be 100% correct which is NOT.
Now instead of posting another rubbish comment to show your immaturity and lack of knowledge do that experiment mentioned above and see how accurate your gauge is and what actual average your car gives.
30 Km/L!! man you are defying official figures of Suzuki i.e. 23.1 Km/L and I have even posted the proof from Suzuki India site. Your New Cultus and indian celerio has got same engines, same sensors, same ECU. Just indian celerio is cheaper in price with some more features.