When it comes to cars, CNG 
stands for Compressed Natural Gas.
CNG could also mean saving worth thousands of rupees per month. It can also mean that you have something to show for after watching An Inconvenient Truth :). Although not many (hardly any!) people here in Pakistan are concerned about their carbon foot print, there are many who would love to save. This little article gives you the low down on CNG for your car, answering questions about CNG safety (exploding cars?!?!) and engine life.
Fuel Savings: It is by all means a great way to save on fuel, given that the fuel prices in Pakistan are rising. A friend of mine, living in Gujranwala, has a Toyota Vitz 2002 on CNG; he is getting Rs 2 to a liter. That is unheard of for petrol as anyone who has done the calculations would know. Would know by heart!
CNG and car performance: Yes, your car will not have the same pick with CNG that it has with Petrol. I used to own a Suzuki Mehran with CNG and the car would actually refuse to go above 90 Kmh when on CNG. On petrol, the car would be flying at 120 (for a Mehran, 120 is definitely ‘flying’!). A friend has a CNG fitted Honda Civic 2001, and the difference in the car’s acceleration is actually quite insignificant; I had to ask him that if the car is on CNG or not, I could not tell while we drove around Lahore. A car engine above 1300 CC will not let you feel the difference between CNG and Petrol, whereas for below 1300 CC, the difference is more in top speed than in pick/acceleration. If you do face drawn out acceleration when on CNG, it is probably because your engine needs some cleanup; oil change, oil and/or air filter replacement etc.
CNG and Engine Life: Getting CNG for your car does NOT affect your engine and does NOT reduce its life in a worrisome way. People in opposition of CNG, do say that ‘Engine life gets reduced from 20 to 15 years after putting in CNG,’ as if they have done the calculations. I would save enough in those 15 years to buy two more cars, and that is the main point of getting CNG; cost savings.
CNG and types of cars: CNG can be fitted in any car that is being driven on the roads of Lahore. I have seen Toyota Land Cruisers on CNG and do plan to put up pictures of a Cruiser that I saw with four cylinders fitted at the back. Mostly people are of the opinion that only Petrol cars can be kitted out with CNG; a modified diesel engine can be converted to CNG. Although I have not heard of such a ‘conversion’, in theory at least CNG and Diesel go good together.
The CNG ‘threat’:There has been incidents of car CNG cylinders exploding. Now this is dangerous. But how real is the threat? As long as your CNG tank is inspected at least after every 5 years (look for an approval stamp sticker), you are good to go. The problem of exploding CNG tanks is due to cheap material being used while fabricating the tank. CNG tanks that do not pass quality standards is not a ‘good-thing-to-have’, it is a must. Make sure you ask for a quality stamp from the workshop, and also know that CNG tanks do not explode; it is so rare that God willing, it will probably never happen if you take the above mentioned precautions.
As the gas, inherently, is compressed, that automatically poses a greater risk than Petrol, which just ‘lies’ in the car petrol tank. So the quality of the car’s CNG tank can not be overstressed; make sure you get the best.
For the nitty-gritty on CNG technology, please check out the CNG page at caradvice.pk’s technology pages. (as per plan, this is where different car technologies will be explained, God willing 
).
