I happen to come across this thread today, and i would like to add that i agree that CNG is a nice add on to the car just like rims and other add ons, but it does ruin your car. it is like installing very fat tyres on ur car, they will give u a good road grip but ur brakes will be pushed to the limit. cars are built for petrol and we should use them in that. i read the calculations that some of u guys did in this thread and they do not contain the price of petrol that u consume when u start your car, nor does that include the price of tuning ur car to get better CNG, every now and then, and nor does it include the price of damage that CNG does to ur engine in the long run. if u take consider all these items then u will see that CNG is way way way more expensive than petrol in the long run. u may be happy about filling ur tank on cng and getting 200kms on it (and that would also be a world record on a 1.3 ltr car) this week, but after 4 weeks when that kit will require tunning and maintenance, then u will end up spending way more than what petrol users spend. but u dont have to listen to me, i am just putting forward my thoughts. u can continue using cng all u want, but i think CNG is atleast a little better on smaller cars as they do not require so much tuning up that 1.3lts cars need. rest is upto u guys, its ur money spend it the way u think is best.