These were my comments on gassing the Altis, valid also for Civic, because both are top of line local assembled cars in Pakistan.
You can drive your Altis on CNG (and in this case reborn Civic), but it would never give the driving pleasure for which you have bought an expensive 1.8 car.
Dear life is short so enjoy it. Saving is good for your economy, but it should not necessarily be your car to make this saving for you.
There are lot of other wasteful and unhealthy pursuits on which we spend blindly, but when it comes to petrol we lose heart.
Always fill a full tank, it really gives you max milage. Save yourself from a shoddy fuel and long queue and also your ride would stay as good as new for a long time.