There is no general formula for calculating the depreciation value for a car. and it depends on many factors including condition of the car, how much km it has run and if any new version of the car has been launched by the company.
However, while counting insurance amount, the value of a car generally depreciated by around 5 percent.
Tata Indica eV2 eLS fuel economy is 25kmpl (ARAI Certified). To know its mileage in city and highways, kindly click on the below link: -