As on date the price of petrol in Malaysia is RM 1.92 per litre and the price of NGV Gas is RM 0.68. There is a clear difference of 65 % between the two fuels.
So,the simplest way to calculate the amount of money that you can save by converting your vehicle to NGV is to multiply the amount of money that you spend on petrol by 65 %.
For example ,if you spend around RM 500 on petrol every month, then you save RM 325 (500 x 65 %) per month on your fuel bill. For every year you save RM 3900 (325 x 12).
Unlike petrol, you need not replace your engine black oil very frequently. So you also save money on the oil cost when you run on NGV. You also save 25 % on the Road Tax !