For this, we would suggest you walk into the nearest dealership as they have a separate department for finance and will be the better person to assist you. You can click on the following link to see the details of the nearest dealership and selecting your city accordingly - Car Showrooms.
In order to improve the mileage, we would suggest you drive slower. Driving fast can reduce your fuel efficiency by up to 33% if you are traveling above 60 kmph. It is best to change gears appropriately and match the gear and the RPM carefully.