Najmul Patani

From a car owner's perspective: I've had both. CNG is cheaper to run per kilometer—it's the most economical fuel option right now. But the conversion cost is high and you lose boot space to that huge tank. Performance takes a slight hit; the car feels a bit sluggish. LPG kits are usually cheaper to install and the performance drop is less noticeable but the fuel itself is more expensive than CNG (though still cheaper than petrol).

Also finding stations is key. In my city CNG pumps are at specific gas stations and often have lines of taxis. LPG for autos (AutoGas) is harder to find now. For home use it's all LPG of course (your cooking cylinder). Environmentally CNG burns cleaner than petrol or diesel emitting less CO2. LPG is also clean but produces more CO2 than CNG.