In the month of September 2006, I got my CNG kit installed in my SANTRO(2002 model). I ran the car for 19000 km till April 2007. In 7 months, I recovered more than I had invested in CNG Kit. As the mileage on AC, while running on petrol in Delhi was Rs 4.25 per km, I managed to save around 2.75 per km or Rs 52000 approx since the instalation of kit.
Now comes the bigger profit - Because, I wanted to buy a new car, I sold off Santro along with CNG Kit. The resale price I got for CNG kit I recieved was Rs 20000/-.
Now, I have purchased an Esteem. I have got CNG retrofitted witha bogger Cylinder. I am sure, I will get good mileage and profits from the same as well.
Since the availability of CNG in Delhi has improved dramatically, its advisable for people using 50 kms per day or more to switch on to CNG. Its safe, clean, lighter than air and light on pocket.