If you don't like it, return it then. You have all the right as a consumer/buyer for any product, especially hefty investments like a car. My A/T unit has been averaging 15km/l for every tank full of unleaded fuel since I bought it. To achieve high gas mileage involves a lot of factors - quality of fuel for example. It's possible that the quality of locally produced fuel here is of lower quality compared to a country say singapore - reason for which emission test for even new cars are not as great as expected.
If you don't really like the car, then return it.
If you don't really like the car, then return it.