Well, after using NGV for almost 4 months, i have this to say to future users. Make sure you do your calculations correct before committing to it. There might be some hidden costs to be included.
You need to include the “after-installation” maintenance costs, such as the regular change of engine oil every 5,000km (installer recommends semi-synthetic at RM128); then the installation of Flashlube which will cost a few hundred plus the regular topping up of Flashlube liquid. The last I calculated, those two alone cost at least RM100 per month. So much for the savings you gain from conversion (some more with the dwindling pump prices). Oh, not to mention that if you are using the sequential system, you will be burning petrol as well at about 1/2 tank to 1 full tank per month (just to start your car and warm the engine before the NGV kicks in). So, make your calculations properly.
Anyway, I am all for the use of NGV since I have already installed it. But I hear a lot of users in the forum justifying the use of NGV with the excuse of cleaner combustion = cleaner environment (what a load of crap!) I think they use the NGV for the cost savings, and cleaner combustion just a by-product they can use as an excuse. If saving the planet is the motivation, I suggest taking the public transport.
Anyway, in the long-run, using NGV will save you money, even if you drive less than 1,000km per month, provided you have paid off your loan. So far, I am saving about RM0.10 per km (at RM2.00 per liter pump price)