Only mileage issue rest great car

Everything is fine except mileage I have driven 6000 kms I'm getting 8/9 per litre still not crossed 10/litre at least 15/litre is ok as per Maruti Suzuki product which are known for good mileage. Few cons front door inside handles makes noise while using it, mine is zxi AT should give better mileage as per company claims..