If fuel economy is your only concern and you wanto keep the car for 5 years.
Look no further then an aqua. Aqua can manage 24km/L in average daily driving.
About batteries in New York prius taxis have crossed 400,000 plus kms.
But a good aqua costs 18.5-19.50.
Don't settle for a locally driven car.
Vitz is a safe bet but it only manages 11-15 different people different reviews i haven't got more then 13.5 on vitz.
Vitz and aqua good cars have atleast a different of 300k.
In between you can definitely look for a manual or a auto Honda city.
But it's a different story Honda city also doesn't goes beyoun 10-13 km/L mark.