Honda city 1.3 manual 5th gen
Or a JDM 660cc, PKDM Cultus
15KMPL might be displayed on the meter but by tank to tank method is realistic if you drive with a light foot in light traffic on roads with minimal braking.
Or if u get a hybrid like prius or aqua which is difficult in your budget, the cost of maintenance/replacing batteries would offset any savings from good fuel economy.