This is the answer I got from an expert for my question.Hope It
may useful to you. At intial level you will not get good mileage figures as a new car takes time to
accustom - the Engine, Piston, Fuel Lines all takes time to lubricate and initial mileage will be low. It
generally takes upto 800 to 1000 kms for your car started to offer a better mileage. While at around 4000 -
5000 kms distance when covered, mileage will be at its best and will stabilize which even gets better on oil
change at 7500 - 10,000 kms. In order to improve the mileage, we would suggest you to drive slower.Driving
fast can reduce your fuel efficiency by up to 33% if you are travelling above 60 mph. It is best to change
gears appropriately and match the gear and the RPM carefully. You have to be careful when going to the tuner.
Make sure the tuning is just to keep your engine running at the proper revs to provide maximum fuel
efficiency. Changing the fuel filter on a regular basis will ensure that your car runs smoothly by letting
only fuel into the engine instead of other residue from the tank and a clean air filter promotes better
combustion which optimizes fuel economy. The tire pressure should be checked at least monthly because properly
inflated tires can improve fuel efficiency by up to 3%. Turning off air conditioner in city driving reduces
stress on your engine which increases fuel economy greatly. Whether you use synthetic of natural oil, using an
additive can improve fuel efficiency by up to 15%. You can keep these things in mind while maintaining your
car.