TAta Zest XT - poor mileage

Pros:- good looks, driving comfort, good interiors. Cons:- fuel economy is pathetic. In chennai city the average is 9.5km per litre (petrol version) in economy mode. Have driven the car for 2000 kms. I complained about the poor mileage during the first service. After the service I was told that everything has been checked and there is no reason to worry about. But the poor mileage experience continues.