Converting cars to run on natural gas

Several years back a friend asked me if it was advisable for him to convert his Toyota Corolla to run on natural gas. The conversion cost was about US$2,800. The price per litre of the natural gas was significantly lower than RON95 petrol. However the key question here is how much does travel everyday to justify the conversion cost and when was the break even point. Dumping US$2,800 for the conversion was not as simple as just modifying the engine, the problem with doing this type of conversions is that once the engine has been converted to run on natural gas, the modifications cannot be reversed. The power and performance of the engine is also not as good when running on natural gas as compared to RON95 petrol. The latent heat created by the natural gas also meant that the engine would be running at higher temperatures and potentially could cause far wear on certain parts of the engine.
After finding out that he only travels an average of 100km a day, I couldn't see the real justification to convert the car to natural gas. His break even point would be about 1 year but that is also dependent on the price of RON95 petrol at that time (which was hovering at RM2.70 per litre) and that price could change at any time.

He proceeded to make the conversion to run on natural gas and within 2 months, the Govt announced the revised RON95 petrol price to RM1.90 per litre. This meant that his break even point just got a lot longer and since the modification is not reversible he is stuck with it. Now he faces problems with getting natural gas supply because he has to queue up with taxis at selected Petronas stations which are only available at few locations across the country and couple that with the small natural gas tank that only provides a short range of 240km per tank.

Conversions like this should only be done for commercial vehicles that clock up more than 300km a day, such as taxis and delivery vehicles.