Like to ride old one, it's my dream to buy new swift in future

Good space, average is good, good millage, car body is too good, maintenance cost almost Rs.3500, easy availability of spareparts, don't getting tired in long drive, getting average of 3.55Rs per Km in CNG (as per current rate) and in petrol getting around 5Rs per Km. Little bit unhappy not getting CNG station everywhere. So If i would like to buy new one in exchange with my old swift lxi, i would like to buy swift in diesel