Good bad, need improvement in millege section

I bought this car in october last week, according to the company it gives you 23kmpl to 25kmpl but my car is giving a millege of 13kmpl in the city 15.6kmpl in the highway, so it is clear that this car does nt give the millege that the company claims, i bought this because of the looks n millege that the company claims but in reality millege needs to be improved.. other, like cabin, seat, head room, leg room, dashboard, gear box music system all working smoothly, i dont have any issue with the looks of the car, its very stylish compact car, looks realy realy good but i am diappointed with the permomance of the car in terms of millege that it is giving..Realy realy disappointed its giving 9-13kmpl in the city and 15-16kmpl in the highway.