CNG happens to be a 3rd class fuel still... its harms are evident too! Do a little cost benifit analysis...
35Ks for installing the CNG at least, saving is worth a few hundred per month only, engine wear doubles, mechanic visits doubles, AC dies, Acceleration and power dies completely, Yes... now spend more and get those CNG engine oils, CNG batteries and bla bla!! its just alternate spending... nothing fruit full! Our awam is lakeer ki faker! they love what everybodys doing!!
Its better to keep a bike and not to use a car for bringing bread and eggs each day! Fuel costs can be controlled, specially when u have a 660cc MIRA giving 16km/ltr... then its just stupid to use CNG, had it been a carby cultus/marghala/alto type car which is hopeless on petrol then it would have been a choice... but???? In Mira!!??