ya average you can say 16% interest rate. for three years. for a car of 7.5lacs in total. assuming you are paying 2lacs down payment and the bank will bear 5.5 lacs. approx with a rough calculation you will pay 2.5 lacs extra to the bank in three years time on 5.5lacs... excluding all the service and process and insurance fee of the car etc.
If you somehow manage to arange money till 3 lacs. I would say to buy car on cash. because used car in 7.5lacs i guess you can only get mehran. so better to arrange 3 lacs in cash and get neat mehran between 92 to 98 model.
Banks can only deal with 5 to 7 years old used car i guess.