@vaqas1 The wiring is alteration based and the meter is not digital, thats why no error shows on the it. 2 errors were resolved when the ECU was manually checked by the electrician, one was of air fuel mixture sensor and other was oil temperature sensor.
I don't wanna go for swapping, this is a standard sized smooth engine.
May be My foot is slightly heavy on local but on motorway I drove the car last week in 5th gear with an average speed of 110km and it gives me just about 13.5 km/l.