Did you drive it because most of the 4 wheels do not give more than 10 or 11KM per liter as per my experience, Please drive it in between full tank because the system can show anything. As advised Gaurav wonderful car but these car but sell it before the warranty expires and note when you sell it do not expect anything as it may be sold at lowest price.
I recommend take it for rent, drive it for a day to get an exact KM.
Thanks.