Pefrect with less budget

Fuel economy should improve , body should have quite thik material and back leg room should give little more space. Mileage is quite bad it should improve. It doesn’t give the perfect mileage as they say from the showroom and from the dealer. Lastly interior space should be there not that less as it given. Lastly thanks to the maruti suzuki for prefect car in the budget of 4.5 lacks. Thank you ??